Latest news

NEW: JUNE 2022 NEWSLETTER

• We list all the latest Java performance related news and articles
  • "Now with very little effort, you can create your own custom full featured Java agent!"
• All the latest Java performance tips extracted in concise form
  • "Request handling entry and exit points are often a good point to target instrumentation."

MAY 2022 NEWSLETTER

• We list all the latest Java performance related news and articles
  • "the configuration to ensure responsiveness needs to consider failure modes including failover and startup"
• All the latest Java performance tips extracted in concise form
  • "There are always queues somewhere. Queue size is NOT a useful metric, since a non-empty queue does not imply a problem, in fact it could imply an efficient use of resources. Focus instead on the metrics that affect response time - median task wait time. The longest wait times are often anomalous - or may need to be targeted specifically depending on your application"

APRIL 2022 NEWSLETTER

• We list all the latest Java performance related news and articles
  • "The techniques used to make it the lowest possible overhead profiler: infrequent sampling, no stack walking, no thread matching or analysis, minimal processing of data"
• All the latest Java performance tips extracted in concise form
  • "A cache pattern decision chart: 1 - if your data is crucial for startup and not highly dynamic, use a file persistent storage mechanism closer to the services to store the data; 2 - if your data is highly dynamic, use a dedicated caching technology that can handle this, with caches closer to the service or lower latency than the primary data store; 3 - if your data is not highly dynamic and can be easily invalidated, use a reverse proxy"

MARCH 2022 NEWSLETTER

• We list all the latest Java performance related news and articles
  • "I explain how to use OpenTelemetry, both with no code changes and by adding custom metrics"
• All the latest Java performance tips extracted in concise form
  • "Keeping a small working set of data improves latency by orders of magnitude as the data can fit in CPU caches"

FEBRUARY 2022 NEWSLETTER

• We list all the latest Java performance related news and articles
  • "it's a very clear well written coverage of all the things that are wrong with using finalize() and the alternatives available to you. If you are an advanced Java developer, you should read it"
• All the latest Java performance tips extracted in concise form
  • "A simple java.lang.ref.Cleaner example to clean up resources (for some obj) instead of implementing a finalize() method would be similar to Cleaner cleaner = Cleaner.create(); Cleaner.Cleanable cleanable = cleaner.register(obj, cleanupRunnableWhenObjGCed) and if you want to execute the clean up early, you can execute cleanable.clean() (which would execute the cleanupRunnableWhenObjGCed runnable immediately. The runnable is never executed more than once even including GCs"

JANUARY 2022 NEWSLETTER

• We list all the latest Java performance related news and articles
  • "What's most interesting is how simple and straightforward the basic implementation of a Java simple agent is. If you want to try it, you can be up and running with your own agent implementation in minutes!"
• All the latest Java performance tips extracted in concise form
  • "The JVM has 3 entry points: agentmain, premain, main. -javaagent uses premain, which also runs on the main thread, and you can have multiple java agents. The agentmain is on it's own thread and if you attach to a JVM you enter this thread. You can have multiple agents but there is only one entry thread"

DECEMBER 2021 NEWSLETTER

• We list all the latest Java performance related news and articles
  • "The four golden signals are often co-dependent. A typical scenario is for saturation to be too high on some resource, causing errors to increase, throughput to start failing (decrease) and latency consequently to increase"
• All the latest Java performance tips extracted in concise form
  • "Virtual threads (aka fibres from project Loom) is more readable and efficient than reactive to multiplex, if you have sufficient memory for the number of virtual threads you want"

NOVEMBER 2021 NEWSLETTER

• We list all the latest Java performance related news and articles
  • "JVM GC logs analyzers from Oracle, HP, IBM, Netflix, Microsoft, Apple and many individual contributors tells us that the GC has been and still is an important target for tuning"
• All the latest Java performance tips extracted in concise form
  • "In the cloud, the footprint matters and is most likely the limiting factor in minimizing cost of a JVM application"

OCTOBER 2021 NEWSLETTER

• We list all the latest Java performance related news and articles
  • "GC log analysis tools are very useful - and now, one of the two commercial GC log analyzers, Censum, has open sourced it's core as GCToolkit."
• All the latest Java performance tips extracted in concise form
  • "Workloads have become memory bound - CPUs spend most of their time waiting for data to reach them, rather than processing that data. This means you often need to focus on optimizing getting data to the CPU to get speedups. Focus on "Instructions per cycle" - production workloads should be around 1.5 if efficient. Note that a stalled CPU is still reported as 100% utilized by the metric"

SEPTEMBER 2021 NEWSLETTER

• We list all the latest Java performance related news and articles
  • "There are a host of options and decisions to make when deciding on how available your application will be, each with consequences to your design, architecture and implementations. Make sure you decide on the availability you want to provide and ensure that you can attain it"
• All the latest Java performance tips extracted in concise form
  • "compare-and-swap is implemented equivalent to a volatile read and write operation on updates, but only a read operation (no write) if the compare fails. So it won't flush memory if the compare fails"

AUGUST 2021 NEWSLETTER

• We list all the latest Java performance related news and articles
  • "All the new performance features in the Java 17 release, the performance benefits from each feature, and how to use the feature"
• All the latest Java performance tips extracted in concise form
  • "To enable asynchronous logging of the JVM logs, use -Xlog:async and if you need to configure the logging buffer size, use eg -XX:AsyncLogBufferSize=1M (there is a dedicated thread for flushing the buffer)"

JULY 2021 NEWSLETTER

• We list all the latest Java performance related news and articles
  • "I explain how the three pillars of Observability (metrics, tracing, logs), fit into overall troubleshooting"
• All the latest Java performance tips extracted in concise form
  • "Shared state that is frequently written to by multiple threads should be avoided, as it fundamentally limits your scalability"

JUNE 2021 NEWSLETTER

• We list all the latest Java performance related news and articles
  • "Scalability and latency are separate performance targets and you need to have separate targets defined so you know where to target your efforts. You can't just assume scalability can also give you your desired latencies."
• All the latest Java performance tips extracted in concise form
  • "System.nanotime can be 2 orders of magnitude slower depending on which timer source the OS uses"

MAY 2021 NEWSLETTER

• We list all the latest Java performance related news and articles
  • "Health checks, metrics, telemetry, logs, tracing, profiling - how do they all fit together? I explain"
• All the latest Java performance tips extracted in concise form
  • "-Xgcpolicy:optthruput is a single generation parallel non-concurrent GC with optional compaction targeted at GC throughput; -Xgcpolicy:gencon is a parallel and concurrent 2-generation GC with concurrent collection in both generations; metronome is an incremental parallel GC with an upper bound on GC pause time; -Xgcpolicy:balanced is like optthruput but reduces the max pause time by doing smaller partial GCs where possible."

APRIL 2021 NEWSLETTER

• We list all the latest Java performance related news and articles
  • "I list the top 5 reasons for using APM"
• All the latest Java performance tips extracted in concise form
  • "Having balanced requests across instances is important, otherwise instances can be overloaded and you can have a cascaded failure of all instances."

MARCH 2021 NEWSLETTER

• We list all the latest Java performance related news and articles
  • "Being able to scale is challenging. Being able to autoscale needs you to understand what metrics determine when you need more (or fewer) resources allocated. Architecting to achieve a queueable application is fundamentally different from the ground up."
• All the latest Java performance tips extracted in concise form
  • "There are three options to handle as much traffic as possible, which can be used in combination: scale (adding sufficient additional capacity to handle the traffic increase); overprovision (already having sufficient additional capacity to handle any traffic increase); queue (temporarily holding requests somewhere and processing when resources are available)."

FEBRUARY 2021 NEWSLETTER

• We list all the latest Java performance related news and articles
  • "All the new performance features in the Java 16 release, the performance benefits from each feature, and how to use the feature - including the news that ZGC is fully concurrent - no pauses over a millisecond"
• All the latest Java performance tips extracted in concise form
  • "Unix domain sockets bypasses the TCP/IP stack with consequential improvements in latency and CPU usage"

JANUARY 2021 NEWSLETTER

• We list all the latest Java performance related news and articles
  • "From JDK 17 Shenandoah will be completely concurrent except for some constant time admin operations - all pauses be under 1 millisecond!"
• All the latest Java performance tips extracted in concise form
  • "Prioritized load shedding works by: Consistently prioritize requests across device types into NON_CRITICAL (does not affect customer experience), DEGRADED_EXPERIENCE (affects customer experience but doesn't prevent primary customer operations), CRITICAL, and score between 1 to 100 for each request given its individual characteristics; progressively throttle requests based on priority; validate by chaos testing (deliberate fault injection) for requests of specific priorities"

DECEMBER NEWSLETTER

• We list all the latest Java performance related news and articles
  • "This momth's memory leak special covers JFR memory leak analysis and native memory leak analysis to add to the previous heap memory leak analysis special"
• All the latest Java performance tips extracted in concise form
  • "ByteBuffer.allocate() (which creates a HeapByteBuffer) has memory allocated in the heap, while ByteBuffer.allocateDirect() (which creates a DirectByteBuffer) has memory allocated in native memory. If you use a HeapByteBuffer, OS I/O calls have to copy the data to and from the buffer; using a DirectByteBuffer allows the OS I/O calls to operate directly on the native buffer so copying can be avoided."

NOVEMBER NEWSLETTER

• We list all the latest Java performance related news and articles
  • "Loom solves the difficulty of avoiding concurrency bugs with a significantly lower amount of debugging complexity thank other concurrency models"
• All the latest Java performance tips extracted in concise form
  • "'Shared mutable state' is what makes concurrency particularly difficult. You can either eliminate one of those 3 words, or you need to use optimistic or pessimistic transactional operations"

OCTOBER NEWSLETTER

• We list all the latest Java performance related news and articles
  • "I used all the best tips I've found over the years to put this together and produced a top notch modern GC tuning guide relevant to JDKs 8-15 - most other material is old or specific to tuning a particular GC algorithm, I've taken a holistic 'tune the JVM' view not a narrow 'tune one GC' view"
• All the latest Java performance tips extracted in concise form
  • "Any collector that has 2 (or more) generations has one tuning consequence: Try to have objects collected in the young generation"

SEPTEMBER NEWSLETTER

• We list all the latest Java performance related news and articles
  • "Java's lasting popularity is because it hits the sweet spot for languages"
• All the latest Java performance tips extracted in concise form
  • "Three primary GC tuning strategies are: Choosing an appropriate collector; adjusting heap sizes; reducing the rate of object allocation and promotion."

AUGUST NEWSLETTER

• We list all the latest Java performance related news and articles
  • "All the new performance features in the Java 15 release, the performance benefits from each feature, and how to use the feature - including the new one that let's you generate compressed heap dumps"

JULY NEWSLETTER

• We list all the latest Java performance related news and articles
  • "I list the top 10 core APM features and the 5 top advanced APM features"
• All the latest Java performance tips extracted in concise form
  • "If more than 35 percent of your performance issues are identified by users before the IT team, then you need to do a better job of identifying potential bottlenecks, errors and constraints"

JUNE NEWSLETTER

• We list all the latest Java performance related news and articles
  • "After decades of every vendor/project/application building their own implementation, we're finally going to have a commonly available implementation and standard from the OpenTelemetry project"
• All the latest Java performance tips extracted in concise form
  • "To achieve 10-100 microseconds latency 99% of the time, you need to target 1% utilization of a core or less - 1% utilization of a core means 1% of the time that a new event comes in you're still dealing with the last event, so 1% of events are slowed"

MAY NEWSLETTER

• We list all the latest Java performance related news and articles
  • "if you have any Serverless I really recommend watching this masterclass"
• All the latest Java performance tips extracted in concise form
  • "Serverless invocation types: synchronous (request/response; errors returned to and retries required by the client); asynchronous (event sent by client then disconnected; event on a queue for the serverless function, serverless function called N times or M seconds - configurable, dependent on throttling - then sent to dead letter queue or on-failure destination if not processed; can route based on success and failure); stream-based (pushed in batches synchronously from eg Kinesis or DynamoDB with retries N times or M seconds; need to handle batches that have one bad event somehow, preferably from the cloud capability eg BisectBatchOnFunctionError); poller-based (poller pulls synchronously from a queue, probably in batches)"

APRIL NEWSLETTER

• We list all the latest Java performance related news and articles
  • "If you're a tools/frameworks/libraries developer, then sorry, you need to work 100 times harder at improving your code in all sorts of ways that may never be used"
• All the latest Java performance tips extracted in concise form
  • "The garbage collector becomes much more active when the application is more active. Activities like queueing puts more pressure on the garbage collector."

MARCH NEWSLETTER

• We list all the latest Java performance related news and articles
  • "your primary GC tuning option is now to select the algorithm rather than the old 'tweaking the algorithm' way"
• All the latest Java performance tips extracted in concise form
  • "The methodology for analyzing memory leaks is four steps: 1. Do I have a leak (and does it needs fixing - use gc logs to see); 2. What is leaking (instances of which classes - compare two heap histograms separated by enough time to see the leak); 3. What is keeping the objects alive (what instances in the app - you need a heap dump to find these); 4. Where is it leaking from (the code where the objects are created and/or assigned - any memory profiler which can sort on GC generations and provide object creation traces)."

FEBRUARY NEWSLETTER

• We list all the latest Java performance related news and articles
  • "All the new performance features in the Java 14 release, the performance benefits from each feature, and how to use the feature - including the new one that gives you an always on production profiler"
• All the latest Java performance tips extracted in concise form
  • "JFR and JMC give you information about your Java application such as events on garbage collection, compilation, classloading, memory allocation, file and socket IO, method profiling data, and much more"

JANUARY NEWSLETTER

• We list all the latest Java performance related news and articles
  • "track your connections and the threads that manage them"
• All the latest Java performance tips extracted in concise form
  • "Shuffle sharding: Shard instances (combine them into small groups) to limit the number of instances a particular request source can reach, so that if that request source causes problems (a noisy neighbour), the number of instances impacted is limited (as opposed to full balancing of requests, where the requests could go to any instance, which could potentially impact all instances); Shuffle the shards so that any random shard can contain instances that overlap other shards giving many more shards, if a source request impacts a shard, other source requests going to other shards which include an impacted instance are only partially affected and since there are many more shards you are much less likely to be using the exact same shard as the bad one."

Previous newsletters

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How to use this site

This site has four main information resources:

• The uncategorized tips page lists many other web pages with Java performance tuning related information. Each web page has its performance tuning tips extracted and listed immediately after the URL is listed. These tips are being categorized, and the tips page links to those categories currently available. If the performance area you are interested in is not yet categorized, send us an email from this page telling us the categorization you'd like to see. In any of the tips pages, use your browser's "find" or "search" option to identify particular tips you are interested in on the page, and follow up by reading the referenced web page if necessary or desired.
• The resources page lists Java performance tuning resources including books, tools, reports, other performance tuning sites of interest, and Java performance tuning discussion groups.
• The news pages are monthly newsletters listing any new Java performance tuning related information, together with Kirk Pepperdine's discussion group roundup and Javva The Hutt.
• The tool reports pages are detailed introductory reports on various Java performance related tools, for both free and commercial tools.

This site has been designed to download almost as fast as possible. (Some stylistic markup and required server-side processing has been used in preference to absolute speed contraints.) The web tree contains very few graphics and almost no complex typesetting markup except for very simple tables, and the main pages can be accessed directly from the menu.

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