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Java Flight Recorder as an Observability Software


Evans: My title is Ben Evans. I am a Senior Principal Software program Engineer at Pink Hat. Earlier than becoming a member of Pink Hat, I used to be lead architect for instrumentation at New Relic. Earlier than that, I co-founded a Java efficiency firm known as jClarity, which was acquired by Microsoft in 2019. Earlier than that, I spent numerous time working with banks and monetary firms, and in addition gaming as nicely. Along with my work in my profession, I am additionally recognized for a few of my work in the neighborhood. I am a Java champion, a JavaOne Rockstar speaker. For six years, I served on the Java Group Course of Government Committee, which is the physique that oversees all new Java requirements. I used to be deeply concerned with the London Java Group, which is likely one of the largest and most influential Java person teams on the planet.


What are we going to speak about? We’ll discuss observability. I believe there’s some context that we actually want to offer round observability, as a result of it is talked about rather a lot. I believe there are nonetheless lots of people, particularly within the Java world, who discover that it is complicated or a bit obscure, or they are not fairly certain precisely what it’s. Truly, that is foolish, as a result of observability is actually not all that conceptually obscure. It does have some ideas which you may not be used to, nevertheless it does not truly take that a lot to clarify them. I need to clarify a bit about what observability is. I need to clarify OpenTelemetry, which is an open supply venture and a set of open requirements, which match into the final framework of observability. Then with these two bits of idea in hand, we will flip and take a look at a expertise known as JFR, or JDK Flight Recorder, which is a incredible piece of engineering, and an awesome supply of information that may be actually helpful for Java builders who care about observability. Then we’ll take a fast look as to the place we’re, take the temperature of our present standing. Then we’ll discuss a bit of bit in regards to the future and roadmap, as a result of I do know that builders at all times love that.

Why Observability?

Let’s kick off by fascinated with what observability is. With a view to actually do this, I need to begin from this query of, why will we need to do it? Why is it crucial? I’ve obtained some fascinating numbers right here. The one I need to draw your consideration to is the one on the left-hand facet, which says roughly 63% of JVMs which can be operating in manufacturing at present are containerized. This quantity has come from our mates at New Relic who publish information. Since I put this deck collectively, they really have a pleasant new consequence out which truly says that the 2022 numbers are literally a bit greater. Now they’re seeing roughly 70% of all JVM primarily based functions being containerized. For enjoyable, on the right-hand facet right here, I am additionally displaying you the breakdown of the Java variations. Once more, these numbers are a few 12 months old-fashioned. The truth is, if we checked out them once more at present, we might see that the truth is, Java 11 has elevated much more than that. Java 11 is now within the lead, very barely over Java 8. I do know that persons are at all times inquisitive about these numbers. Clearly, they are not an ideal proxy for the Java market as a complete as a result of it is simply New Relic’s prospects, nevertheless it nonetheless represents a pattern of tens of tens of millions of JVMs. I believe Gartner estimates that round about 1% of all manufacturing JVMs present up within the New Relic information. Not an ideal dataset by any means, however actually a really fascinating one.

The large takeaway that I need you to get out from right here is that cloud native is more and more our actuality, 70% of functions are containerized. That quantity continues to be rising, and rising in a short time. It relies upon upon the market section, in fact. It relies upon upon the maturity that particular person organizations have, however it’s nonetheless an enormous quantity. It’s nonetheless a critical pattern that I believe we have to take critically for a lot of causes, however notably as a result of it has been such a quick rising section. Containerization has occurred actually remarkably rapidly. When an business adopts a brand new observe as quickly and as wholesale as they’ve on this case, then I believe that that is an indication that it’s essential take it critically and to pay some consideration to it.

Why has this occurred? As a result of observability actually helps resolve an issue which it exists in different architectures, nevertheless it’s notably obvious in cloud native, and that is a rise in complexity. We see these with issues like microservices, we see it with sure different facets of cloud native architectures as nicely. Which is that as a result of there’s simply extra stuff in a cloud native structure, extra providers there, there’s all types of latest applied sciences, that conventional APM, Utility Efficiency Monitoring, it is what APM stands for, these forms of approaches simply aren’t actually as appropriate for cloud native. We have to do one thing new and one thing which is extra appropriate.

Historical past of APM (Utility Efficiency Monitoring)

To place this into some context, to justify it a bit of bit, we will look again 15 years, we return to 2007. I used to be working at Morgan Stanley, we actually had APM software program that we had been deploying into our manufacturing environments. They had been the primary era of these forms of applied sciences, however they did exist 15 years in the past. We did get helpful info out of them. Let’s keep in mind what the world of software program growth was like 15 years in the past, it was a very totally different world. We had launch cycles that we measured in months, not in days or hours. Very often, the functions that I used to be working with again in these days, we might have possibly a launch each six weeks, possibly a launch each couple of months. That was the cadence at which new variations of the software program got here out. This was earlier than microservices. We had a service primarily based structure. These had been massive scale, fairly monolithic providers. In fact, we ran this all in our personal information facilities or rented information facilities. There was no notion of an on-demand cloud in the identical approach that we have now today.

What this implies is 2 issues, as a result of the architectures are steady for a interval of months, a superb operations group can get a deal with on how the structure behaves. They’ll develop instinct for the way the totally different items of the structure match collectively, the issues that may go flawed. In case you have a way of what can go flawed, you may just remember to collect information at these factors and see whether or not issues are going to go flawed. You find yourself with a typical view of an structure like this, this conventional 3-tier structure. It is nonetheless a basic information supply JVM degree for utility providers, internet servers, and a few clustering and cargo balancing applied sciences. Fairly customary stuff. What can break? The load balancers can break. The net servers largely are simply serving static content material, aren’t doing an awesome deal. Sure, you can push a nasty config or some dangerous routing to the net layer, however in observe when you do this, you are going to discover it fairly rapidly. The clustering software program can have some barely odd failure modes, and so forth. It is not that difficult. There’s simply not the identical degree of stuff that may go flawed that we see for cloud native.

Distributed System Working On OpenShift

Here is a extra trendy instance. I work for Pink Hat, so in fact, I’ve to indicate you at the least one slide which has obtained OpenShift on it. There we have now a bunch of various issues. What you may discover right here is that it is a far more complicated and far more subtle structure. We have now some bespoke providers. We have an EAP service there. We have Quarkus, which is Pink Hat’s Kubernetes native Java deployment. We have even obtained some issues which are not written in Java, we have got Node.js. We have additionally obtained some issues that are nonetheless labeled as providers, however they’re truly far more like home equipment. When we have now Kafka, for instance, Kafka is a knowledge transport layer. It is shifting info from place to position and sharing it between providers. It is not numerous bespoke coding that is occurring there, as a substitute, that’s one thing which is extra like infrastructure than a bit of bespoke code. Right here, just like the clear separation between the tiers, is far more blurry. We have an awesome admixture of microservices and infrastructural parts like Kafka, and so forth. The information layer continues to be there, nevertheless it’s now augmented by a a lot better complexity for providers in that a part of the structure.

IoT/Cloud Instance

We even have architectures which look nothing like conventional 3-tier architectures. It is a serverless instance. This one actually is cloud native. This one actually is the factor that will probably be very troublesome to construct with conventional IT architectures. Right here we have now IoT, so the web of issues. We have now a bunch of sensors coming in from anyplace. Then we have now some kind of server and even serverless provisioning, which produces an IoT stream job which is fed right into a important datastore. Then we have now different parts that are watching that serverless datastore, and have some machine studying mannequin that is being utilized excessive of it. Now, the parts are literally less complicated in some methods. Lots of the complexity has been hidden, and is being dealt with by the cloud supplier themselves for us. That is the place I am a lot nearer to a serverless sort of deployment.

How Do We Perceive Cloud-Native Apps?

This mainly brings us to the center of how and why cloud native functions are totally different. They are much extra complicated. They’ve extra providers. They’ve extra parts. The topology, the way in which that the providers interconnect with one another is much extra difficult. There are extra sources of change, and that change is happening extra quickly. This has moved us a great distance away from the kinds of architectures that I’d have been coping with on the early level in my profession. Not solely is that complexity and that extra speedy change a significant factor, we additionally should perceive that there are new applied sciences with genuinely new behaviors of the sort that we have now by no means seen earlier than, issues like there are providers which scale dynamically. There are, in fact, containers. There are issues like Kafka. There are perform as a service, and serverless applied sciences. Then lastly, in fact, there’s Kubernetes, which is a large matter in and of its personal proper. That is our world. These are the issues that we have now to face. These are the challenges. That is why we have to do issues otherwise.

Consumer Perspective

Having stated that, regardless of all of that further complexity and all of that further change in our panorama, sure questions, sure facets, we nonetheless want solutions to. We nonetheless want solutions to the kinds of questions like, what’s the total well being of the answer. What about root trigger evaluation? What about efficiency bottlenecks? Is this modification dangerous? Have I launched some regression, by altering the software program and doing a rollout? Total, what does the shopper take into consideration all of this? Key questions, they’re at all times true on each sort of structure you deploy, whether or not that is an old-fashioned 3-tier structure, all through to the most recent and biggest cloud native structure. These considerations, these items that we care about are nonetheless the identical. That’s the reason observability. We have now a brand new world of cloud native, and we require the identical solutions to a few of the usual questions, and possibly a number of new solutions to a couple new questions as nicely. Broadly, we have to adapt our notion of what it’s to offer good service and to have the instruments and the capabilities to try this. That is why observability.

What Is Observability?

What’s observability, precisely? There’s lots of people which have talked about this. I believe that numerous the dialogue round it’s overcomplicated. I do not assume that observability is definitely that obscure conceptually. The way in which that I’ll clarify it’s like this. Initially, we instrument our programs and functions to gather the info that we have to reply these person degree questions that we had, that we had been simply speaking a few second or two in the past. You ship that information exterior of your manufacturing system. You ship it to someplace utterly totally different, which is an remoted exterior system. The rationale why, as a result of when you do not, when you try and retailer and analyze that information inside your manufacturing system, in case your system is down, you could not be capable to perceive or analyze the info, as a result of you will have a dependency on the system which is inflicting the outage. For that motive, you ship it to someplace that is remoted and exterior.

After getting that information, you may then use issues like a question language, or virtually like an experimental strategy of wanting on the information, of digging into it and attempting to see what is going on on by asking open-ended questions. That flexibility is essential, as a result of it is that what offers you with the insights. You do not essentially know what you are going to have to ask whenever you begin attempting to determine, what’s the root reason behind this outage. Why are we seeing issues within the system? That flexibility, the unknown unknowns. The questions you did not know it’s essential ask. That is very key for what makes a system an observability system somewhat than only a monitoring system. In the end, in fact the muse of that is programs management idea, which is how nicely can we perceive the inner state of a system from exterior of it. That is a reasonably theoretical underpinning. We’re within the practitioner strategy right here. We’re concerned about what insights that would lead you to taking motion about your total system. Are you able to observe? Not simply single piece, however all of it.

Complexity of Microservice Architectures

Now the complexity of microservice structure begins to return in. It is not simply that there are bigger numbers of smaller providers. It is not simply that there are a number of individuals who care about this Dev, DevOps, and administration. It is also issues just like the heterogeneous tech stacks. In trendy functions, you do not construct each service or each element out of the identical tech stack. Then lastly, once more, touched on Kubernetes, service price to scale. Very often that is run dynamically or robotically today. That further layer of complexity is added to what we have now with microservices.

The Three Pillars

To assist with diagnosing all of this, we have now an idea of what is known as the three pillars of observability. This idea is a bit of tiny bit controversial. A number of the suppliers of observability options and a few of the thinkers within the house, declare that this isn’t truly that useful a mannequin. My tackle it’s that, particularly for people who find themselves simply coming to the sector and who’re new to observability, that that is truly a fairly good psychological mannequin. As a result of these are issues that individuals might already be barely accustomed to. It may possibly present them with a helpful onramp to get into the info and into the observability mindset. Then they will resolve whether or not or to not discard the psychological mannequin later or not. Metrics, logs, and traces. These are very totally different information sorts. They behave otherwise and have totally different properties.

A metric is only a quantity that describes a selected course of or an exercise, the variety of transactions in, for example, a 10-second window. That is a metric. The CPU utilization on a selected container. That is a metric. Discover, it is a timestamp, and it is a single quantity measured over a hard and fast interval of time mainly. A log is an immutable report of an occasion that occurred at a cut-off date. That blurs the excellence between a log and an occasion. A log may simply be an entry in a Syslog, or an utility log, good previous Log4j or one thing like that. It is perhaps one thing else as nicely. Then a hint. A hint is a bit of information which is used to indicate what was triggered by a person person degree request. Metrics, probably not tied to specific requests. Traces, very a lot tied to a selected request, and logs, someplace within the center. We’ll discuss extra in regards to the totally different facets of information that these items have.

Is not This Simply APM with New Advertising Phrases?

For those who had been of a cynical thoughts, you may ask, is not this simply APM with new advertising? Here is why. Here is 5 explanation why I believe it isn’t. Vastly diminished vendor lock-in. The open specification of the protocols on the wire, the open sourcing of at the least a few of the parts, particularly the shopper facet parts that you just put into your utility, these massively assist to cut back vendor lock-in. That helps hold distributors within the house aggressive, and it helps hold them trustworthy. As a result of when you have the power to change wire protocol, and possibly you solely want to alter a shopper element, then meaning that you would be able to simply migrate to a different vendor do you have to want to. Associated to that, additionally, you will see standardized structure patterns and the truth that as a result of individuals at the moment are cooperating on protocols, cooperating on requirements, and on the shopper parts, we will now begin to have a discourse amongst architects and amongst practitioners as to how we construct these items out in a dependable and a sustainable approach. That results in higher structure observe, which additionally then feeds again into the protocols and parts. Transferring on from that, we additionally see that the shopper parts will not be the one items which can be being developed. There may be an growing amount and high quality of backend parts as nicely.

Open Supply Strategy

On this new strategy, we will see that we have began from the standpoint of instrumenting the shopper facet, which on this case actually means the functions. The truth is, most of these items are going to be server parts. It is usually considered being shopper facet for the observability protocols. It will imply issues like Java brokers and different parts that we will place into our code, whether or not that is bespoke or the infrastructural parts which we’ll additionally have to combine with. From there, we’ll ship the info over the wire right into a separate system, which is marked right here as information assortment. This element too is prone to be open supply, at the least for the receiving half. Then we additionally require some information processing. The primary two steps at the moment are very closely dominated by open supply parts. For information processing, that course of continues to be ongoing. It’s nonetheless potential to both use an open supply element or a vendor for that half. The subsequent step, we’re closing the loop to carry it again round to the person once more is visualization. Once more, there are good tales right here each from vendor code and from open supply options. The market continues to be growing for these last two items.

Observability Market At the moment

By way of at present’s market, and what’s truly in use, there was a current survey by the CNCF, the Cloud Native Computing Basis. They discovered that Prometheus, which is a barely older metrics expertise, might be probably the most broadly used observability expertise round at present. They discovered that this was utilized by roughly 86% of all tasks that they surveyed. That is in fact a self-reported survey, and solely the individuals who had been actively and concerned with observability could have responded to this. It is vital to deal with this information with an appropriate quantity of seasoning. It is a large quantity, and it might not have as a lot statistical validity as we’d assume. The venture that we’re going to spend so much of time speaking about, which is OpenTelemetry, was the second most generally used venture at 49%. Then another instruments as nicely like Fluentd and Jaeger.

What takeaways do we have now from this? One of many level which is fascinating is that 72% of respondents make use of as much as 9 totally different instruments. There may be nonetheless a scarcity of consolidation. Even amongst the parents who’re already concerned about observability, and producing and adopting it inside their organizations, over one-third of them complain that their group lacks correct technique for this. It’s nonetheless early days. We’re already beginning to see some indicators of consolidation. The rationale why we’re focusing and we’re so on OpenTelemetry is as a result of the OpenTelemetry utilization is rising sharply. It is risen to 49% in simply a few years. Prometheus has been round for lots longer, and it appears to have largely reached market saturation. Whereas OpenTelemetry is simply nonetheless in some facets shifting out of beta, it isn’t totally GA but. But, it is already being utilized by about half of the parents who’re adopting observability as a complete. Specifically, Jaeger, which was a tracing answer, have determined to finish of life their shopper libraries. Jaeger is pivoting to be a tracing backend for its shopper and its information ingest libraries, to change over utterly to utilizing OpenTelemetry. That is only one signal of how the market is already starting to consolidate.

That is a part of the method which we see the place API monitoring historically dominated by proprietary distributors, now we’re beginning to transfer into this inflection level the place we’re shifting from proprietary to open supply led options. Extra of the distributors are switching to open supply. After I was at New Relic, I used to be one of many individuals who led that swap of New Relic’s code base from being primarily proprietary on the instrumentation facet, to being utterly open supply. In the midst of seven months, one of many final issues I did at New Relic earlier than I left was helped oversee the open sourcing of about $600 million price of mental property. The market is certainly all heading on this basic route. One of many applied sciences, one of many key issues behind that is OpenTelemetry. Let’s have a look and let’s examine what OpenTelemetry truly is.

What Is OpenTelemetry?

OpenTelemetry is a set of codecs, open requirements, and libraries. It isn’t about information ingest, backend, or offering visualizations. It’s in regards to the parts which finish customers will match into their functions and their infrastructure. It’s designed to be very versatile, and it is extremely explicitly cross-platform, it’s not only a Java customary. Java is only one implementation of it. There are others for the entire main languages you may consider at totally different ranges of maturity. Java is a really mature implementation. We additionally see issues like .NET, and Node, and Go are all pretty mature as nicely. Different languages, Python, Ruby, PHP, Rust, are at various phases of that maturity lifecycle. It’s potential to get OpenTelemetry to work on high of naked metallic or simply in VMs, however there isn’t a getting away from the truth that it is extremely positively a cloud-first expertise. The CNCF have fostered this, and they’re answerable for the usual.

What Are Elements of OpenTelemetry?

There are actually three items to it that you just may need to take a look at. The 2 large ones are the API and the SDKs. The API is what the builders of instrumentation and of the OpenTelemetry customary itself have a tendency to make use of. As a result of they include the interfaces, and from there, you are able to do issues like, you may write an occasion exporter, you may write attribute libraries. The precise customers, the applying homeowners, the tip customers, will usually configure the SDK. The SDK is an implementation of the API. It is the default one, and it is the one you get by default. While you obtain OpenTelemetry, you get the API, you additionally get the SDK as a default implementation of that API. That then is the idea which you’ve got for instrumenting your utility utilizing OpenTelemetry, and that will probably be your start line when you’re new to the venture. There may be additionally the plugin interfaces, that are utilized by a small group of parents who’re concerned about creating new plugins and lengthening the OpenTelemetry framework.

What you need to draw your consideration to is that they describe these 4 ensures. The API is assured for 3 years, plugin interfaces are assured for one 12 months, and so is the SDK, mainly. It is price noting that the totally different parts, metrics, logs, and tracing, are at totally different statuses at totally different factors of their lifecycle. Presently, the one factor which is taken into account in scope for assist is tracing. Though the metrics piece will in all probability additionally come into assist very quickly when it reaches 1.0. Some organizations relying upon the way in which you consider assist, may think about these will not be notably lengthy timescales. It is going to be fascinating to see what particular person distributors will do when it comes to whether or not they honor these ensures or whether or not they may deal with them at the least. The truth is, assist for longer than this.

Listed here are our parts. That is actually what makes up OpenTelemetry. The specification comprising the API, the SDK, information and semantic conventions. These are cross-language and cross-platform. All implementations should have the identical view, so far as potential, as to what these issues imply. Every particular person language then additionally wants not solely an API and an SDK, however we have to instrument the entire libraries and frameworks and functions that we have now accessible. That ought to work so far as potential, utterly out of the field. That instrumentation piece is a separate element from the specification and the SDK. Lastly, one different crucial element of the OpenTelemetry suite is what we name the collector. The collector is a barely problematic title, as a result of when individuals consider a collector, they consider one thing which goes to retailer and course of their information for them. It does not do this. What it truly is, is a really succesful community protocol terminator. It is in a position to communicate a complete number of totally different community codecs, and it successfully acts as a switching station, or a router, or a site visitors terminator. It is all about receiving, processing, and re-exporting telemetry information in no matter format that it might probably discover it in. These are the first OpenTelemetry parts.

JDK Flight Recorder (JFR)

The subsequent part is all about JFR. It’s a fairly good profiling instrument. It has been round for a very long time. It was initially first in Java 7, the primary launch of Java from Oracle, which is now nicely over 10 years in the past. It is obtained this fascinating historical past as a result of Oracle did not invent it, they purchased it after they purchased BEA Methods. Lengthy earlier than they did the take care of Solar Microsystems, they purchased BEA, and BEA had their very own JVM known as JRockit. JFR initially stood for JRockit Flight Recorder. After they merged it into HotSpot with Java7, it turned Java Flight Recorder, after which after they open sourced it, as a result of from Java 7 as much as Java 11, JFR was a proprietary instrument. It did not have an open supply implementation. You could possibly solely use it in manufacturing when you had been ready to pay Oracle for a license. In Java 11, JDK Flight Recorder was added to OpenJDK, renamed to JDK Flight Recorder, and now everyone can use it.

It is a very good profiling instrument. It is extraordinarily low overhead. Oracle declare that it provides you a few 1% influence. I believe that is in all probability overstating the case. It relies upon, in fact, an awesome deal on what you truly acquire. The extra information you acquire, the extra you disturb the method that is beneath statement. It is virtually like quantum mechanics, the extra you take a look at one thing and the extra you observe it, the extra you disturb it and fiddle with it. I’ve actually seen on an affordable information assortment profile round about 3%. For those who’re ready to be extra mild contact on that, possibly you will get it down even additional.

Historically, JFR information is displayed in a GUI console known as Mission Management, or JMC. That is high quality, nevertheless it has two issues that we will discuss. JFR by default generates an output file. It generates a recording file like an airplane black field, and JMC, Mission Management solely means that you can load in a single file at a time. Then you’ve got the issue that, when you’re wanting throughout a whole cluster, you want plenty of GUI home windows open as a way to see the totally different telemetry information from the totally different machines. That is not usually how we need to do issues for observability. At first sight, if it does not seem like JFR, is that appropriate? We’ll have to speak about how we get round that.

Utilizing Flight Recorder

How does it work? You can begin it with a command line flag. It generates this output file, and there are a few pre-configured profiles, they name them, which can be utilized to find out what information is captured. As a result of it generates an output file and dumps it to a disk, and due to the utilization of command line flags, this is usually a little bit of a problem in containers, as we’ll see. Here is what a few of the startup flags may seem like. We have a Java -XX:StartFlightRecorder, after which we have got a length, after which a filename to dump it out to. This backside instance will let you begin a flight recording. When the method begins, it’ll run for 200 seconds, after which it’ll dump out the file. For lengthy operating processes, that is clearly not nice, as a result of as a substitute what’s taking place is that you’ve got solely obtained the primary 200 seconds of the VM. In case your course of is up for days, that is truly not all that useful.

There’s a command known as jcmd. Jcmd is used not simply to regulate JFR, however it may be used to regulate many facets of the Java digital machine. For those who’re on the machine’s console, you can begin and cease and management JFR from the command line. Once more, this isn’t actually that helpful for containers and for DevOps, as a result of in lots of circumstances, with trendy containers and trendy deployments, you may’t log into the machine. How do you get into it, as a way to subject the command, as a way to begin the recording? There are all types of practices you are able to do to mitigate this. You may set issues up in order that JFR is configured as a hoop buffer. What meaning is the buffer is consistently operating and it is recording the final nevertheless many seconds or nevertheless many megabytes of JFR info, after which you may set off JFR to dump that buffer out as a file.

Demo – JFR Command line

Here is one I made earlier. This utility is named heapothesys. That is by our mates and colleagues at Amazon. It’s a reminiscence benchmarking instrument. We do not need to do an excessive amount of. Let’s give this a length of 30 seconds to run somewhat than the three minutes. Let’s simply change the filename as nicely simply so I do not obliterate the final one which I’ve. There we go. You may see that I’ve began this up, you may see that the recording is working. In about 30 seconds we must always get an output to say that we have completed. The HyperAlloc benchmark, which is a part of a listing known as heapothesys, is a really helpful benchmark for enjoying with the reminiscence subsystem. I take advantage of it quite a bit for a few of my testing and a few of my analysis into rubbish assortment. Okay, so right here we go, we have now now obtained a brand new file, there it’s, hyperalloc_qcon. From the command line, there’s truly a JFR command. Right here we go, jfr print. There’s a great deal of information, plenty of issues to do with GC configuration, and all types of issues, code cache statistics, all types of issues that we’d need, plenty of issues to do within the module system.

Here is plenty of CPULoad occasions. For those who look very rigorously, you may see that they’re about as soon as a second. It is offering ticks which might simply be become metrics for CPU utilization, and so forth, as nicely. You see, we have got plenty of good numbers right here. We have the jvmUser, the jvmSystem, and the entire of the machine as nicely. We are able to do a lot of these issues with the command line. What else can we do from the command line? Let’s simply reset this again to 180. Now I am simply going to take the entire element out so we’re not going to start out at startup. As an alternative, I will run that, take a look at Jps from right here, and now I can do jcmd. We’ll simply go away that operating for a brief period of time. Now we will cease it. I forgot to offer it a filename and to dump it. In addition to the beginning and cease instructions, I forgot to do a dump within the meantime. You truly additionally wanted a JFR dump in there as nicely. That is only a temporary instance of displaying you ways you can do a few of that with the command line.

The opposite factor which you are able to do is definitely programmatic. You may truly take a file, and this is one I made earlier. Inside the trendy eleven-plus JDK, you may see that we even have a few entries, RecordedEvent and RecordingFile. This allows us to course of the file. Down right here, for instance, on line 19, we will soak up a RecordingFile, after which course of it shortly loop the place we take particular person occasions, that are of this kind, jdk.jfr.shopper.RecordedEvent. Then we will have a way of processing the occasions. I take advantage of a sample for programmatically dealing with JFR occasions, which entails constructing these handlers. I’ve an interface known as a RecordedEventHandler, which mixes each the buyer and the predicate. Successfully, you check to see whether or not or not you’ll deal with this occasion. Then when you can, you then devour it. Here is the check occasion, this is the predicate. Then the opposite occasion that we’ll usually additionally see is the buyer, so is the, settle for. Then, mainly, what this boils all the way down to is one thing like a G1 handler. This one can deal with a bunch of various occasions, G1HeapSummary, GCHeapSummary, and GCPhaseParallel. Then the settle for occasion seems to be like this. We mainly take a look at the incoming title, and determine which of those it’s. Then delegate to an overload of settle for. That is just a few code for programmatically dealing with occasions like this and for producing CSV recordsdata from them.

JFR Occasion Streaming

One of many different issues which has additionally occurred with current variations of JFR, is that this transfer away from coping with recordsdata. JFR recordsdata are nice if what you are doing is essentially efficiency evaluation. Sadly, it has issues, for doing observability and for long run, at all times on manufacturing profiling. What we have to have is a few telemetry stream of knowledge. Step one in the direction of that is in Java 14, which got here out over two years in the past now. That mainly supplied a mode for JFR, the place you can get a callback. As an alternative of getting to start out and cease recordings and management them, you can simply arrange a thread, which stated, each time one in all these occasions that I’ve registered seems, please name me again, and I’ll reply to the occasion.

Instance JFR Java Agent

In fact, a technique that you just may need to do that is with a Java agent. You could possibly, for instance, produce some quite simple code like this. That is truly a whole working Java agent. We have a premain methodology, so we are going to connect. Then we have now a run methodology. I’ve cheated a bit of tiny bit, as a result of there is a StreamEventSender object which I have never applied, and I am displaying you what it does. Principally, it sends up the occasions to something that we might need. You may think that these simply go over the community. Now as a substitute of getting a RecordingFile, we have now a RecordingStream. Then all we have to do is to inform it which occasions we need to allow, so CPULoad. There’s additionally one known as JavaMonitorEnter. This mainly is an occasion which helps you to know whenever you’re holding a lock for too lengthy, in order that we’ll get a JFR occasion triggered each time a synchronized lock is held by any thread for greater than 10 milliseconds. Lengthy held locks successfully is what you may detect with that. You set these two up with the callback of which is the onEvent traces. Then lastly, you name our begin. That methodology doesn’t return, as a result of now your thread has simply been despatched up as an occasion loop, and it’ll obtain occasions from the JFR subsystem as issues occur.

What Is Present Standing of OpenTelemetry?

How can we marry up JFR with OpenTelemetry? Let’s take a fast take a look at what the standing of OpenTelemetry truly is. Traces are 1.0. They have been 1.0 for I take into consideration a 12 months now. They let you monitor the progress of a single request. They’re mainly changing older open requirements, together with OpenTracing, together with Jaeger’s shopper libraries. Distributed tracing inside OpenTelemetry is consuming the lunch of all of these tasks. It appears very clear that that’s how the business, not simply in Java, goes to do tracing going forwards. Metrics is so near hitting 1.0. The truth is, it might go 1.0 as early as this week. For JVM, meaning each utility and runtime metrics. There may be nonetheless some work to do to make the JVM metrics, those which can be produced straight by the VM itself, that’s, those that we’ll use JFR for, as a way to get that to utterly align. It is the main target of ongoing work. Metrics is now very shut as nicely. Logging continues to be in draft state. We don’t anticipate that we’ll get a 1.0 log customary till late 2022 on the earliest. Something which isn’t a hint or a metric is taken into account to be a log. There’s some debate about whether or not or not, in addition to logs, we’d like occasions as a associated or subtype of logs that we have now.

Totally different Areas Have Totally different Rivals

The maturities are totally different in some methods. Traces, OTel is mainly out in entrance. Prometheus, there’s already numerous people utilizing Prometheus, particularly for Kubernetes. Nonetheless, it is much less nicely established elsewhere and it hasn’t actually moved quite a bit these days. I believe that could be a house the place OTEL and a mixed strategy which makes use of OTel traces and OTel metrics can actually doubtlessly make some headway. The logging panorama is extra difficult, as a result of there are many present options on the market. It is not clear to me that OTel logging will make that a lot of an influence but. It’s extremely early days for that final one. Basically, OpenTelemetry goes to be declared as 1.0 as quickly as traces and metrics are completed. The general customary as a complete will go 1.0 very quickly.

Java and OpenTelemetry

Let’s discuss Java and OpenTelemetry. We have talked about a few of these ideas already, however now let’s attempt to weave the threads collectively, and produce it into the realm of what a Java developer or Java DevOps particular person will probably be anticipated to do day-to-day. Initially, we have to discuss a bit of tiny bit about handbook versus computerized instrumentation. In Java, not like another languages, there are actually two methods of doing issues. There may be handbook instrumentation, the place you’ve got full management. You may write no matter you want. You could possibly instrument no matter you want, however it’s important to do all of it your self, and you’ve got a direct coupling to the observability libraries and APIs. There’s additionally the horrible risk of human error right here, as a result of what occurs when you do not instrument the correct issues, otherwise you assume one thing is not vital, and it seems to be vital? Not solely do you not have the info, however you could not know that you do not have it. Guide instrumentation may be error inclined.

Alternatively, some individuals like computerized instrumentation, this requires you to make use of a Java agent, or to make use of a framework which robotically helps OpenTelemetry. Quarkus, for instance, has computerized inbuilt OTel assist. You do not want a Java agent. You need not instrument every thing manually. As an alternative, the framework will do quite a bit to assist you. It is not a free lunch, you continue to require some config. Specifically, whenever you’ve obtained a fancy utility, you will have to inform it sure issues to not instrument simply to ensure you do not drown in an excessive amount of information. The draw back of computerized is there might be a startup time influence when you’re utilizing a Java agent. There is perhaps some efficiency penalties as nicely. It’s a must to measure that. It’s a must to decide for your self which of those two routes is best for you. There’s additionally one thing which is a bit of little bit of a hybrid strategy, which you can do as nicely. Totally different functions will attain totally different options.

Inside the open-telemetry GitHub org, there are three important tasks that we care about throughout the Java world. There’s opentelemetry-java, that is the principle instrumentation repo. It contains the API, and it contains the SDK. There may be opentelemetry-java-instrumentation. That is the instrumentation for libraries and different parts and issues that you would be able to’t straight modify. It additionally offers an agent which lets you instrument your functions as nicely. There’s additionally opentelemetry-java-contrib. That is the standalone libraries, the issues that are accompaniments to this. It is also the place something which is meant for the principle repos, both the principle OTel Java or the Java instrumentation repo, they go into contrib first. The largest items of labor which can be in Java contrib proper now are gathering of metrics by JMX, and JFR assist, which continues to be very a lot in beta, we have not completed it but. We’re nonetheless engaged on it.

This leads us to an structure which seems to be quite a bit like this. You may have functions with libraries which rely straight upon the API. Then we have now an SDK, which offers us with exporters, which can ship the info throughout the wire. For tracing, we are going to at all times require some configuration as a result of we have to present the place the traces are despatched to. Usually, traces will probably be sampled. It isn’t usually potential to gather information about each single transaction and each single person request that’s despatched in. We have to pattern, and the query is, how will we do the sampling? Can we pattern every thing on the identical charge? Some individuals, notably the Honeycomb people, very a lot need to pattern errors extra regularly. There may be an argument to be made, the errors must be sampled at 100%, 200 oks, possibly not. There’s additionally the query about whether or not it is best to pattern uniformly or whether or not it is best to use another distribution for figuring out the way you pattern. Specifically, might you do some lengthy tail sampling, the place sluggish requests are additionally sampled extra closely than the requests which full nearer to the meantime? Metrics assortment can also be dealt with by the SDK. We have now a metrics supplier which is normally international as an entry level. We have now three issues that we care about, we have now counters, which solely ever improve, so transaction rely, one thing like that. We have now measures that are values aggregated over time, and observers that are probably the most complicated sort, and supply successfully a callback.

Aggregation in OpenTelemetry

One of many issues which we must also say about OpenTelemetry, is that OpenTelemetry is an enormous scale venture. It’s designed to scale as much as very massive programs. In some methods, it is an instance of a system, which is constructed for the massive scale, however continues to be usable at medium and small scales. As a result of it is designed for giant programs, it aggregates. Aggregation occurs, not notably in your app code or beneath the management of the person, however within the SDKs. It is potential to construct complicated architectures, which do a number of aggregations at a number of scales.

Standing of OTel Metrics

The place are we with metrics? Metrics for manually instrumented code are steady. The wire format is steady. We’re 100% manufacturing prepared on the code. The one factor which we nonetheless may need a slight little bit of variation on, and as quickly as the following launch drops, that will not change, is the precise nature or which means of the info that is being collected from OTel metrics. If you’re prepared to start out deploying OpenTelemetry, I’d not maintain again at this level on taking the OTel metrics as nicely.

Issues with Guide Instrumentation

There are numerous issues with handbook instrumentation. Attempting to maintain it updated is troublesome. You may have affirmation biases that you could be not know what’s vital. What counts as vital will in all probability change as the applying adjustments over time. There is a nasty downside with handbook instrumentation, which is that you just very often solely discover out what is actually vital to your utility in an outage, which matches towards the entire goal of observability. The entire goal of observability is to not need to predict what’s vital, to have the ability to ask these questions the place you did not know you’d have to ask them on the outset. Guide instrumentation goes towards that aim. For that motive, plenty of individuals like to make use of computerized instrumentation.

Java Brokers

Principally, Java brokers set up a hook. I did present an instance of this earlier on, which incorporates a premain methodology. That is known as a pre-registration hook. It runs earlier than the principle methodology of your Java utility. It means that you can set up transformer lessons, which have the power to rewrite code because it’s seen. Principally, there’s an API with a quite simple hook, there is a class known as instrumentation. You may add bytecode transformers and weavers, after which add them in as class transformers into instrumentation. That is the place the actual work is completed, in order that when the premain methodology exits, these transformers have been registered. These transformers will probably be rewritten and in a position to spin up new code and to insert bytecode into lessons as they’re loaded. There are key libraries for doing this. In OpenTelemetry we use the one known as Byte Buddy. There’s additionally a very talked-about bytecode rewriting library known as ASM, which is used internally by the JDK.

The Java agent that is supplied by OpenTelemetry can connect to any Java 8 and above utility. It dynamically injects bytecode to seize the traces. It helps numerous the favored libraries and frameworks utterly out of the field. It makes use of the OTLP exporter. OTLP is the OpenTelemetry Line Protocol. The community protocol which is actually Google Protocol Buffers over gRPC, which is an HTTP/2 model of protocol.


If you wish to take a look on the tasks, the OpenTelemetry Java might be one of the best place to start out. It’s a massive and complicated venture. I’d very a lot advocate that you just take a while to look by it when you’re concerned about turning into a developer on it. For those who simply need to be a person, I’d simply devour a broadcast artifact from Maven Central or out of your vendor.


Observability is a rising pattern for cloud native builders. There are nonetheless loads of individuals utilizing issues like Prometheus and Jaeger at present. OpenTelemetry is coming. It’s fairly staggering how rapidly it’s rising and what number of new builders are onboarding to it. Java has nice information sources which might be used to drive OpenTelemetry, together with expertise like Java brokers and JFR. There are lively open supply work to carry these two strands collectively.


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