CHANGELOG.md

Changelog

[4.3]

Features

• #1547: Native lock profiling
• #1566: Filter cpu/wall profiles by latency
• #1568: Expose async-profiler metrics in Prometheus format
• #1628: async-profiler.jar as Java agent; remote control via JMX

Improvements

• #1140: FlameGraph improvements: legend, hot keys, new toolbar icons
• #1530: Timezone switcher between Local and UTC time in Heatmaps
• #1582: Support --include/--exclude options for JFR to Heatmap/OTLP/pprof conversion
• #1624: Compatibility with OTLP v1.9.0
• #1629: Harden crash protection in StackWalker

Breaking changes

• #1277: New timeSpan field in WallClockSample events
• #1518: Deprecate check command
• #1590: Support compilation on modern JDKs. Drop JDK 7 support

Bug fixes

• #1599: Workaround for the kernel PERF_EVENT_IOC_REFRESH bug
• #1596: Do not block any signals during execution of a custom crash handler
• #1584: JfrReader loops on corrupted recordings
• #1555: Parse FlameGraph title from HTML input
• #1621: loop and timeout options do not work together
• #1641: Unwind vDSO correctly on Linux-ARM64
• #1648: Fix stop sequence in Profiler::start
• #1575: Fix CodeCache memory leak in lock profiling while looping
• #1558: Fix record-cpu bug when kernel stacks are not available
• #1651: Do not record CPU frame for non-perf samples
• #1614, #1615, #1617, #1623: Fix races related to VM termination

[4.2.1] - 2025-11-22

Bug fixes

• #1599: Workaround for the kernel PERF_EVENT_IOC_REFRESH bug
• #1596: Do not block any signals during execution of a custom crash handler

[4.2] - 2025-10-20

Features

• Java Method Tracing and Latency Profiling
  • #1421: Latency profiling
  • #1435: Allow wildcards in Instrument profiling engine
  • #1499: --trace option with per-method latency threshold
• System-wide process sampling on Linux
  • #1411: --proc option to record profiler.ProcessSample events
• VMStructs stack walker by default
  • #1539: Use VMStructs stack walking mode by default
  • #1537: Support comptask and vtable features
  • #1517: Use JavaFrameAnchor to find top Java frame
  • #1449: Special handling of prologue and epilogue of compiled methods

Improvements

• #1475: Add CPUTimeSample event support to jfrconv
• #1414: Per-thread flamegraph option in JFR heatmap converter
• #1526: Expose JfrReader dictionary that maps osThreadId to javaThreadId
• #1448: Thread name in OpenTelemetry output
• #1413: Add time_nanos and duration_nanos to OTLP profiles
• #1450: Unwind dylib stubs as empty frames on macOS
• #1416: Add synthetic symbols for Mach-O stubs/trampolines
• Allow cross-compilation for 32-bit platforms

Bug fixes

• #1515: Fix UnsatisfiedLinkError when tmpdir is set to a relative path
• #1500: Detect if calloc calls malloc for nativemem profiling
• #1427: Re-implement SafeAccess crash protection
• #1417: Two wall-clock profilers interfere with each other

Project Infrastructure

• #1527: GHA: replace macos-13 with macos-15-intel
• #1510: Add option to retry tests
• #1508: Add more GHA jobs to cover JDK versions on ARM
• #1502: Fix job dependencies between integration tests and builds
• #1466: Add Liberica JDK on Alpaquita Linux to the CI
• Made integration tests more stable overall

[4.1] - 2025-07-21

Features

• Experimental support for the OpenTelemetry profiling signal
  • #1188: OTLP output format and dumpOtlp Java API
  • #1336: JFR to OTLP converter
• JDK 25 support
  • #1222: Update VMStructs for JDK 25
• Productize native memory profiling
  • #1193: Full nativemem support on macOS
  • #1254: Fixed Nativemem tests on Alpine
  • #1269: Native memory profiling now works with jemalloc
  • #1323: nativemem shows allocations inside async-profiler itself

Improvements

• #1174: Detect JVM in non-Java application and attach to it
• #1223: Native API to add custom events in JFR recording
• #1259: --all option to collect all possible events simultaneously
• #1286: Record which CPU a sample was taken on
• #1299: Skip last 10% allocations for leak detection
• #1300: Allow profiling kprobes/uprobes with --fdtransfer
• #1366: Rewrite jfrconv executable to shell
• #1400: Unwind checksum and digest intrinsics on ARM64
• #1357, #1389: VMStructs-based stack unwinding for alloc and nativemem profiling

Bug fixes

• #1251: --ttsp option does not work on Alpine
• #1264: Guard hook installation with dlopen/dlclose
• #1319: SIGSEGV in PerfEvents::walk
• #1350: Disable JFR OldObjectSample event in jfrsync mode
• #1358: Do not dereference jmethodIDs on JDK 26
• #1374: Correctly check if profiler is preloaded
• #1380: Workaround clang type promotion bug
• #1387: JFR writer crashes when using cstack=vmx
• #1393: Improve stack walking termination logic: no endless unknown frames
• Stack unwinding fixes for ARM64

Project Infrastructure

• #1129: Command-line option to filter tests
• #1262: Include asprof.h in async-profiler release package
• #1271: Release additional binaries with debug symbols
• #1274: Add Corretto 8 to the test matrix
• #1246, #1226: Run tests on Amazon Linux and Alpine Linux
• #1360: Auto-generated clang-tidy review comments
• #1373: Save all generated test logs for debug purposes
• Fixed flaky tests (#1282, #1307, #1376)

[4.0] - 2025-04-08

Features

• #895, #905: jfrconv binary and numerous converter enhancements
• #944: Interactive Heatmap
• #1064: Native memory leak profiler
• #1002: An option to display instruction addresses
• #1007: Optimize wall clock profiling
• #1073: Productize VMStructs-based stack walker: --cstack vm/vmx
• #1169: C API for accessing thread-local profiling context

Improvements

• #923: Support JDK 23+
• #952: Solve musl and glibc compatibility issues; link libstdc++ statically
• #955: --libpath option to specify path to libasyncProfiler.so in a container
• #1018: --grain converter option to coarsen flame graphs
• #1046: --nostop option to continue profiling outside --begin/--end window
• #1178: --inverted option to flip flame graphs vertically
• #1009: Allows collecting allocation and live object traces at the same time
• #925: An option to accumulate JFR events in memory instead of flushing to a file
• #929: Load symbols from debuginfod cache
• #982: Sample contended locks by overflowing interval bucket
• #993: Filter native frames in allocation profile
• #896: FlameGraph: Alt+Click to remove stacks
• #1097: FlameGraph: N/Shift+N to navigate through search results
• #1182: Retain by-thread grouping when reversing FlameGraph
• #1167: Log when no samples are collected
• #1044: Fall back to ctimer for CPU profiling when perf_events are unavailable
• #1068: Count missed samples when estimating total CPU time in ctimer mode
• #1142: Use counter-timer register for timestamps on ARM64
• #1123: Support clock=tsc without a JVM
• #1070: Demangle Rust v0 symbols
• #1007: Use ExecutionSample event for CPU profiling and WallClockSample for Wall clock profiling
• #1011: Obtain can_generate_sampled_object_alloc_events JVMTI capability only when needed
• #1013: Intercept java.util.concurrent locks more efficiently
• #759: Discover available profiling signal automatically
• #884: Record event timestamps early
• #885: Print error message if JVM fails to load libasyncProfiler
• #892: Resolve tracepoint id in asprof
• Suppress dynamic attach warning on JDK 21+

Bug fixes

• #1143: Crash on macOS when using thread filter
• #1125: Fixed parsing concurrently loaded libraries
• #1095: jfr print fails when a recording has empty pools
• #1084: Fixed Logging related races
• #1074: Parse both .rela.dyn and .rela.plt sections
• #1003: Support both tracefs and debugfs for kernel tracepoints
• #986: Profiling output respects loglevel
• #981: Avoid JVM crash by deleting JNI refs after GetMethodDeclaringClass
• #934: Fix crash on Zing in a native thread
• #843: Fix race between parsing and concurrent unloading of shared libraries
• #1147, #1151: Deadlocks with jemalloc and tcmalloc profilers
• Stack walking fixes for ARM64
• Converter fixes for jfrsync profiles
• Fixed parsing non-PIC executables and shared objects with non-standard section layout
• Fixed recursion in pthread_create when using native profiling API
• Fixed crashes on Alpine when profiling native apps
• Fixed warnings with -Xcheck:jni
• Fixed "Unsupported JVM" on OpenJ9 JDK 21
• Fixed DefineClass crash on OpenJ9
• JfrReader should handle custom events properly
• Handle truncated JFRs

Project Infrastructure

• Restructure and update documentation
• Implement test framework; add new integration tests
• Unit test framework for C++ code
• Run CI on all supported platforms
• Test multiple JDK versions in CI
• Add GHA to validate license headers
• Add Markdown checker and formatter
• Add Issue and Pull Request templates
• Add Contributing Guidelines and Code of Conduct
• Run static analyzer and fix found issues (#1034, #1039, #1049, #1051, #1098)
• Provide Dockerfile for building async-profiler release packages
• Publish nightly builds automatically

[3.0] - 2024-01-20

Features

• #724: Binary launcher asprof
• #751: Profile non-Java processes
• #795: AsyncGetCallTrace replacement
• #719: Classify execution samples into categories in JFR converter
• #855: ctimer mode for accurate profiling without perf_events
• #740: Profile CPU + Wall clock together
• #736: Show targets of vtable/itable calls
• #777: Show JIT compilation task
• #644: RISC-V port
• #770: LoongArch64 port

Improvements

• #733: Make the same libasyncProfiler work with both glibc and musl
• #734: Support raw PMU event descriptors
• #759: Configure alternative profiling signal
• #761: Parse dynamic linking structures
• #723: --clock option to select JFR timestamp source
• #750: --jfrsync may specify a list of JFR events
• #849: Parse concatenated multi-chunk JFRs
• #833: Time-to-safepoint JFR event
• #832: Normalize names of hidden classes / lambdas
• #864: Reduce size of HTML Flame Graph
• #783: Shutdown asprof gracefully on SIGTERM
• Better demangling of C++ and Rust symbols
• DWARF unwinding for ARM64
• JfrReader can parse in-memory buffer
• Support custom events in JfrReader
• An option to read JFR file by chunks
• Record GCHeapSummary events in JFR

Bug fixes

• Workaround macOS crashes in SafeFetch
• Fixed attach to OpenJ9 on macOS
• Support UseCompressedObjectHeaders aka Lilliput
• Fixed allocation profiling on JDK 20.0.x
• Fixed context-switches profiling
• Prefer ObjectSampler to TLAB hooks for allocation profiling
• Improved accuracy of ObjectSampler in --total mode
• Make Flame Graph status line and search results always visible
• loop and timeout options did not work in some modes
• Restart interrupted poll/epoll_wait syscalls
• Fixed stack unwinding issues on ARM64
• Workaround for stale jmethodIDs
• Calculate ELF base address correctly
• Do not dump redundant threads in a JFR chunk
• check action prints result to a file
• Annotate JFR unit types with @ContentType

[2.9] - 2022-11-27

Features

• Java Heap leak profiler
• meminfo command to print profiler's memory usage
• Profiler API with embedded agent as a Maven artifact

Improvements

• --include/--exclude options in the FlameGraph converter
• --simple and --dot options in jfr2flame converter
• An option for agressive recovery of [unknown_Java] stack traces
• Do not truncate signatures in collapsed format
• Display inlined frames under a runtime stub

Bug fixes

• Profiler did not work with Homebrew JDK
• Fixed allocation profiling on Zing
• Various jfrsync fixes
• Symbol parsing fixes
• Attaching to a container on Linux 3.x could fail

[2.8.3] - 2022-07-16

Improvements

• Support virtualized ARM64 macOS
• A switch to generate auxiliary events by async-profiler or FlightRecorder in jfrsync mode

Bug fixes

• Could not recreate perf_events after the first failure
• Handle different versions of Zing properly
• Do not call System.loadLibrary, when libasyncProfiler is preloaded

[2.8.2] - 2022-07-13

Bug fixes

• The same .so works with glibc and musl
• dlopen hook did not work on Arch Linux
• Fixed JDK 7 crash
• Fixed CPU profiling on Zing

Changes

• Mark interpreted frames with _[0] in collapsed output
• Double click selects a method name on a flame graph

[2.8.1] - 2022-06-10

Improvements

• JFR to pprof converter (contributed by @NeQuissimus)
• JFR converter improvements: time range, collapsed output, pattern highlighting
• %n pattern in file names; limit number of output files
• --lib to customize profiler library path in a container
• profiler.sh list command now works without PID

Bug fixes

• Fixed crashes related to continuous profiling
• Fixed Alpine/musl compatibility issues
• Fixed incomplete collapsed output due to weird locale settings
• Workaround for JDK-8185348

[2.8] - 2022-05-09

Features

• Mark top methods as interpreted, compiled (C1/C2), or inlined
• JVM TI based allocation profiling for JDK 11+
• Embedded HTTP management server

Improvements

• Re-implemented stack recovery for better reliability
• Add loglevel argument
• Do not mmap perf page in --all-user mode
• Distinguish runnable/sleeping threads in OpenJ9 wall-clock profiler
• --cpu converter option to extract CPU profile from the wall-clock output

[2.7] - 2022-02-14

Features

• Experimental support for OpenJ9 VM
• DWARF stack unwinding

Improvements

• Better handling of VM threads (fixed missing JIT threads)
• More reliable recovery from not_walkable AGCT failures
• Do not accept unknown agent arguments

[2.6] - 2022-01-09

Features

• Continuous profiling; loop and timeout options

Improvements

• Reliability improvements: avoid certain crashes and deadlocks
• Smaller and faster agent library
• Minor jfr and jfrsync enhancements (see the commit log)

[2.5.1] - 2021-12-05

Bug fixes

• Prevent early unloading of libasyncProfiler.so
• Read kernel symbols only for perf_events
• Escape backslashes in flame graphs
• Avoid duplicate categories in jfrsync mode
• Fixed stack overflow in RedefineClasses
• Fixed deadlock when flushing JFR

Improvements

• Support OpenJDK C++ Interpreter (aka Zero)
• Allow reading incomplete JFR recordings

[2.5] - 2021-10-01

Features

• macOS/ARM64 (aka Apple M1) port
• PPC64LE port (contributed by @ghaug)
• Profile low-privileged processes with perf_events (contributed by @Jongy)
• Raw PMU events; kprobes & uprobes
• Dump results in the middle of profiling session
• Chunked JFR; support JFR files larger than 2 GB
• Integrate async-profiler events with JDK Flight Recordings

Improvements

• Use RDTSC for JFR timestamps when possible
• Show line numbers and bci in Flame Graphs
• jfr2flame can produce Allocation and Lock flame graphs
• Flame Graph title depends on the event and --total
• Include profiler logs and native library list in JFR output
• Lock profiling no longer requires JVM symbols
• Better container support
• Native function profiler can count the specified argument
• An option to group threads by scheduling policy
• An option to prepend library name to native symbols

Notes

• macOS build is provided as a fat binary that works both on x86-64 and ARM64
• 32-bit binaries are no longer shipped. It is still possible to build them from sources
• Dropped JDK 6 support (may still work though)

[2.0] - 2021-03-14

Features

• Profile multiple events together (cpu + alloc + lock)
• HTML 5 Flame Graphs: faster rendering, smaller size
• JFR v2 output format, compatible with FlightRecorder API
• JFR to Flame Graph converter
• Automatically turn profiling on/off at --begin/--end functions
• Time-to-safepoint profiling: --ttsp

Improvements

• Unlimited frame buffer. Removed -b option and 64K stack traces limit
• Additional JFR events: OS, CPU, and JVM information; CPU load
• Record bytecode indices / line numbers
• Native stack traces for Java events
• Improved CLI experience
• Better error handling; an option to log warnings/errors to a dedicated stream
• Reduced the amount of unknown stack traces

Changes

• Removed non-ASL code. No more CDDL license

[1.8.4] - 2021-02-24

Improvements

• Smaller and faster agent library

Bug fixes

• Fixed JDK 7 crash during wall-clock profiling

[1.8.3] - 2021-01-06

Improvements

• libasyncProfiler.dylib symlink on macOS

Bug fixes

• Fixed possible deadlock on non-HotSpot JVMs
• Gracefully stop profiler when terminating JVM
• Fixed GetStackTrace problem after RedefineClasses

[1.8.2] - 2020-11-02

Improvements

• AArch64 build is now provided out of the box
• Compatibility with JDK 15 and JDK 16

Bug fixes

• More careful native stack walking in wall-clock mode
• resume command is not compatible with JFR format
• Wrong allocation sizes on JDK 8u262

[1.8.1] - 2020-09-05

Improvements

• Possibility to specify application name instead of pid (contributed by @yuzawa-san)

Bug fixes

• Fixed long attach time and slow class loading on JDK 8
• UnsatisfiedLinkError during Java method profiling
• Avoid reading /proc/kallsyms when --all-user is specified

[1.8] - 2020-08-10

Features

• Converters between different output formats:
  • JFR -> nflx (FlameScope)
  • Collapsed stacks -> HTML 5 Flame Graph

Improvements

• profiler.sh no longer requires bash (contributed by @cfstras)
• Fixed long attach time and slow class loading on JDK 8
• Fixed deadlocks in wall-clock profiling mode
• Per-thread reverse Flame Graph and Call Tree
• ARM build now works with ARM and THUMB flavors of JDK

Changes

• Release package is extracted into a separate folder

[1.7.1] - 2020-05-14

Features

• LBR call stack support (available since Haswell)

Improvements

• --filter to profile only specified thread IDs in wall-clock mode
• --safe-mode to disable selected stack recovery techniques

[1.7] - 2020-03-17

Features

• Profile invocations of arbitrary Java methods
• Filter stack traces by the given name pattern
• Java API to filter monitored threads
• --cstack/--no-cstack option

Improvements

• Thread names and Java thread IDs in JFR output
• Wall clock profiler distinguishes RUNNABLE vs. SLEEPING threads
• Stable profiling interval in wall clock mode
• C++ function names as events, e.g. -e VMThread::execute
• check command to test event availability
• Allow shading of AsyncProfiler API
• Enable CPU profiling on WSL
• Enable allocation profiling on Zing
• Reduce the amount of unknown_Java samples

[1.6] - 2019-09-09

Features

• Pause/resume profiling
• Allocation profiling support for JDK 12, 13 (contributed by @rraptorr)

Improvements

• Include all AsyncGetCallTrace failures in the profile
• Parse symbols of JNI libraries loaded in runtime
• The agent autodetects output format by the file extension
• Output file name patterns: %p and %t
• -g option to print method signatures
• -j can increase the maximum Java stack depth
• Allocaton sampling rate can be adjusted with -i
• Improved reliability on macOS

Changes

• -f file names are now relative to the current shell directory

[1.5] - 2019-01-08

Features

• Wall-clock profiler: -e wall
• -e itimer mode for systems that do not support perf_events
• Native stack traces on macOS
• Support for Zing runtime, except allocation profiling

Improvements

• --all-user option to allow profiling with restricted perf_event_paranoid (contributed by @jpbempel)
• -a option to annotate method names
• Improved attach to containerized and chroot'ed JVMs
• Native function profiling now accepts non-public symbols
• Better mapping of Java thread names (contributed by @KirillTim)

Changes

• Changed default profiling engine on macOS
• Fixed the order of stack frames in JFR format

[1.4] - 2018-06-24

Features

• Interactive Call tree and Backtrace tree in HTML format (contributed by @rpulle)
• Experimental support for Java Flight Recorder (JFR) compatible output

Improvements

• Added units: ms, us, s and multipliers: K, M, G for interval argument
• API and command-line option -v for profiler version
• Allow profiling containerized JVMs on older kernels

Changes

• Default CPU sampling interval reduced to 10 ms
• Changed the text format of flat profile

[1.3] - 2018-05-13

Features

• Profiling of native functions, e.g. malloc

Improvements

• JDK 9, 10, 11 support for heap profiling with accurate stack traces
• root can now profile Java processes of any user
• -j option for limiting Java stack depth

[1.2] - 2018-03-05

Features

• Produce SVG files out of the box; flamegraph.pl is no longer needed
• Profile ReentrantLock contention
• Java API

Improvements

• Allocation and Lock profiler now works on JDK 7, too
• Faster dumping of results

Changes

• total counter of allocation profiler now measures heap pressure (like JMC)

[1.1] - 2017-12-03

Features

• Linux Perf Events profiling: CPU cycles, cache misses, branch misses, page faults, context switches etc.
• Kernel tracepoints support
• Contended monitor (aka intrinsic lock) profiling
• Individual thread profiles

Improvements

• Profiler can engage at JVM start and automatically dump results on exit
• list command-line option to list supported events
• Automatically find target process ID with jps tool
• An option to include counter value in collapsed output
• Friendly class names in allocation profile
• Split allocations in new TLAB vs. outside TLAB

Changes

• Replaced -m modes with -e events
• Interval changed from int to long

[1.0] - 2017-10-09

Features

• CPU profiler without Safepoint bias
• Lightweight Allocation profiler
• Java, native and kernel stack traces
• FlameGraph compatible output