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jattach
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GitHub - jattach/jattach: JVM Dynamic Attach utility
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The utility to send commands to a JVM process via Dynamic Attach mechanism.
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All-in-one jmap + jstack + jcmd + jinfo functionality in a single tiny program.
No installed JDK required, works with just JRE. Supports Linux containers.
Attach APIã®è»œéãªãã€ãã£ãããŒãžã§ã³ã ãšãããŠããŸãïŒAttach APIã䜿ã£ãŠããããã§ã¯ãããŸããïŒã
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- load : load agent library
- properties : print system properties
- agentProperties : print agent properties
- datadump : show heap and thread summary
- threaddump : dump all stack traces (like jstack)
- dumpheap : dump heap (like jmap)
- inspectheap : heap histogram (like jmap -histo)
- setflag : modify manageable VM flag
- printflag : print VM flag
- jcmd : execute jcmd command
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Release Concatenate jcmd arguments · jattach/jattach · GitHub
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$ jattach [pid] [command]
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JRE しか入ってない Pod で Java の heap dump を取りたい / Get heap dump on JRE container - Speaker Deck
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$ lsb_release -a No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu 22.04.4 LTS Release: 22.04 Codename: jammy $ uname -srvmpio Linux 5.15.0-94-generic #104-Ubuntu SMP Tue Jan 9 15:25:40 UTC 2024 x86_64 x86_64 x86_64 GNU/Linux
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Server.java
import java.io.IOException; import java.io.OutputStream; import java.net.InetSocketAddress; import java.nio.charset.StandardCharsets; import java.time.LocalDateTime; import java.util.concurrent.Executors; import com.sun.net.httpserver.HttpServer; public class Server { public static void main(String... args) throws IOException { int port = Integer.parseInt(System.getProperty("server.port", "8000")); HttpServer server = HttpServer.create(new InetSocketAddress(port), 0); server.createContext("/", exchange -> { String message = "Hello World"; byte[] bytes = message.getBytes(StandardCharsets.UTF_8); exchange.sendResponseHeaders(200, bytes.length); try (OutputStream os = exchange.getResponseBody()) { os.write(bytes); } }); server.setExecutor(Executors.newCachedThreadPool()); server.start(); System.out.printf("[%s] start lightweight http server.%n", LocalDateTime.now()); } }
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$ javac --release 8 Server.java
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$ java --version openjdk 21.0.1 2023-10-17 OpenJDK Runtime Environment (build 21.0.1+12-Ubuntu-222.04) OpenJDK 64-Bit Server VM (build 21.0.1+12-Ubuntu-222.04, mixed mode, sharing)
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$ /usr/lib/jvm/java-8-openjdk-amd64/bin/java -version openjdk version "1.8.0_392" OpenJDK Runtime Environment (build 1.8.0_392-8u392-ga-1~22.04-b08) OpenJDK 64-Bit Server VM (build 25.392-b08, mixed mode) $ /usr/lib/jvm/java-11-openjdk-amd64/bin/java --version openjdk 11.0.21 2023-10-17 OpenJDK Runtime Environment (build 11.0.21+9-post-Ubuntu-0ubuntu122.04) OpenJDK 64-Bit Server VM (build 11.0.21+9-post-Ubuntu-0ubuntu122.04, mixed mode, sharing) $ /usr/lib/jvm/java-17-openjdk-amd64/bin/java --version openjdk 17.0.9 2023-10-17 OpenJDK Runtime Environment (build 17.0.9+9-Ubuntu-122.04) OpenJDK 64-Bit Server VM (build 17.0.9+9-Ubuntu-122.04, mixed mode, sharing) $ /usr/lib/jvm/java-21-openjdk-amd64/bin/java --version openjdk 21.0.1 2023-10-17 OpenJDK Runtime Environment (build 21.0.1+12-Ubuntu-222.04) OpenJDK 64-Bit Server VM (build 21.0.1+12-Ubuntu-222.04, mixed mode, sharing)
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$ /usr/lib/jvm/java-21-openjdk-amd64/bin/javac -bash: /usr/lib/jvm/java-21-openjdk-amd64/bin/javac: ãã®ãããªãã¡ã€ã«ããã£ã¬ã¯ããªã¯ãããŸãã $ /usr/lib/jvm/java-21-openjdk-amd64/bin/jcmd -bash: /usr/lib/jvm/java-21-openjdk-amd64/bin/jcmd: ãã®ãããªãã¡ã€ã«ããã£ã¬ã¯ããªã¯ãããŸãã
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## Java 8 $ /usr/lib/jvm/java-8-openjdk-amd64/bin/java -Dserver.port=8080 Server [2024-02-18T15:26:46.535] start lightweight http server. $ curl localhost:8080 Hello World ## Java 11 $ /usr/lib/jvm/java-11-openjdk-amd64/bin/java -Dserver.port=8080 Server [2024-02-18T15:27:56.106774] start lightweight http server. $ curl localhost:8080 Hello World ## Java 17 $ /usr/lib/jvm/java-17-openjdk-amd64/bin/java -Dserver.port=8080 Server [2024-02-18T15:28:22.205653282] start lightweight http server. $ curl localhost:8080 Hello World ## Java 21 $ /usr/lib/jvm/java-21-openjdk-amd64/bin/java -Dserver.port=8080 Server [2024-02-18T15:28:43.328222880] start lightweight http server. $ curl localhost:8080 Hello World
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jattachãã€ã³ã¹ããŒã«ããŸãããã Ubuntu Linuxã®å Žåã¯aptã§ã€ã³ã¹ããŒã«ããããšãã§ããã®ã§ãã
$ sudo apt install jattach
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$ apt show jattach Package: jattach Version: 2.0-1 Priority: optional Section: universe/java Origin: Ubuntu Maintainer: Ubuntu Developers <ubuntu-devel-discuss@lists.ubuntu.com> Original-Maintainer: Sven Hoexter <hoexter@debian.org> Bugs: https://bugs.launchpad.net/ubuntu/+filebug Installed-Size: 47.1 kB Depends: libc6 (>= 2.34) Homepage: https://github.com/apangin/jattach Download-Size: 12.4 kB APT-Sources: https://mirrors.edge.kernel.org/ubuntu jammy/universe amd64 Packages Description: JVM Dynamic Attach utility all in one jmap jstack jcmd jinfo jattach is a utility implementing commands for the JVM Dynamic Attach mechanism. Instead of installing a complete JDK you can use this small utility to query information from your running JVM.
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$ curl -LO https://github.com/jattach/jattach/releases/download/v2.2/jattach-linux-x64.tgz $ tar xf jattach-linux-x64.tgz
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$ ./jattach
jattach 2.2 built on Jan 10 2024
Usage: jattach <pid> <cmd> [args ...]
Commands:
load threaddump dumpheap setflag properties
jcmd inspectheap datadump printflag agentProperties
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$ /usr/lib/jvm/java-21-openjdk-amd64/bin/java -Xmx512M -Dtarget.port=8080 Server [2024-02-18T15:41:31.273379805] start lightweight http server.
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$ ./jattach jcmd
jattach 2.2 built on Jan 10 2024
Usage: jattach <pid> <cmd> [args ...]
Commands:
load threaddump dumpheap setflag properties
jcmd inspectheap datadump printflag agentProperties
$ ./jattach jcmd -l
jcmd is not a valid process ID
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- load : load agent library
- properties : print system properties
- agentProperties : print agent properties
- datadump : show heap and thread summary
- threaddump : dump all stack traces (like jstack)
- dumpheap : dump heap (like jmap)
- inspectheap : heap histogram (like jmap -histo)
- setflag : modify manageable VM flag
- printflag : print VM flag
- jcmd : execute jcmd command
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$ ./jattach 3745 jstack Connected to remote JVM JVM response code = -1 Operation jstack not recognized!
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$ ./jattach 3745 properties Connected to remote JVM JVM response code = 0 #Sun Feb 18 15:47:26 JST 2024 file.encoding=UTF-8 file.separator=/ java.class.path=. java.class.version=65.0 java.home=/usr/lib/jvm/java-21-openjdk-amd64 java.io.tmpdir=/tmp java.library.path=/usr/java/packages/lib\:/usr/lib/x86_64-linux-gnu/jni\:/lib/x86_64-linux-gnu\:/usr/lib/x86_64-linux-gnu\:/usr/lib/jni\:/lib\:/usr/lib java.runtime.name=OpenJDK Runtime Environment java.runtime.version=21.0.1+12-Ubuntu-222.04 java.specification.name=Java Platform API Specification java.specification.vendor=Oracle Corporation java.specification.version=21 java.vendor=Private Build java.vendor.url=Unknown java.vendor.url.bug=Unknown java.version=21.0.1 java.version.date=2023-10-17 java.vm.compressedOopsMode=32-bit java.vm.info=mixed mode, sharing java.vm.name=OpenJDK 64-Bit Server VM java.vm.specification.name=Java Virtual Machine Specification java.vm.specification.vendor=Oracle Corporation java.vm.specification.version=21 java.vm.vendor=Private Build java.vm.version=21.0.1+12-Ubuntu-222.04 jdk.debug=release line.separator=\n native.encoding=UTF-8 os.arch=amd64 os.name=Linux os.version=5.15.0-94-generic path.separator=\: stderr.encoding=UTF-8 stdout.encoding=UTF-8 sun.arch.data.model=64 sun.boot.library.path=/usr/lib/jvm/java-21-openjdk-amd64/lib sun.cpu.endian=little sun.io.unicode.encoding=UnicodeLittle sun.java.command=Server sun.java.launcher=SUN_STANDARD sun.jnu.encoding=UTF-8 sun.management.compiler=HotSpot 64-Bit Tiered Compilers target.port=8080 ãçç¥ã user.timezone=Asia/Tokyo
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Connected to remote JVM JVM response code = 0
jattach [pid] agentPropertiesã
$ ./jattach 3745 agentProperties Connected to remote JVM JVM response code = 0 #Sun Feb 18 15:53:30 JST 2024 sun.java.command=Server sun.jvm.args=-Xmx512M -Dtarget.port\=8080 sun.jvm.flags=
jattach [pid] threaddumpã§ã¹ã¬ãããã³ãã
$ ./jattach 3745 threaddump
Connected to remote JVM
JVM response code = 0
2024-02-18 15:50:41
Full thread dump OpenJDK 64-Bit Server VM (21.0.1+12-Ubuntu-222.04 mixed mode, sharing):
Threads class SMR info:
_java_thread_list=0x00007fe7a40024f0, length=13, elements={
0x00007fe8340ae000, 0x00007fe8340af680, 0x00007fe8340b1110, 0x00007fe8340b2750,
0x00007fe8340b3cf0, 0x00007fe8340b5830, 0x00007fe8340b6ef0, 0x00007fe8340c5100,
0x00007fe8340c8a50, 0x00007fe8340fa8f0, 0x00007fe83410aa70, 0x00007fe8340162d0,
0x00007fe7a4000fe0
}
"Reference Handler" #9 [3754] daemon prio=10 os_prio=0 cpu=0.49ms elapsed=549.96s tid=0x00007fe8340ae000 nid=3754 waiting on condition [0x00007fe80db0e000]
java.lang.Thread.State: RUNNABLE
at java.lang.ref.Reference.waitForReferencePendingList(java.base@21.0.1/Native Method)
at java.lang.ref.Reference.processPendingReferences(java.base@21.0.1/Reference.java:246)
at java.lang.ref.Reference$ReferenceHandler.run(java.base@21.0.1/Reference.java:208)
"Finalizer" #10 [3755] daemon prio=8 os_prio=0 cpu=0.32ms elapsed=549.96s tid=0x00007fe8340af680 nid=3755 in Object.wait() [0x00007fe80da0e000]
java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait0(java.base@21.0.1/Native Method)
- waiting on <0x00000000e1f01670> (a java.lang.ref.NativeReferenceQueue$Lock)
at java.lang.Object.wait(java.base@21.0.1/Object.java:366)
at java.lang.Object.wait(java.base@21.0.1/Object.java:339)
at java.lang.ref.NativeReferenceQueue.await(java.base@21.0.1/NativeReferenceQueue.java:48)
at java.lang.ref.ReferenceQueue.remove0(java.base@21.0.1/ReferenceQueue.java:158)
at java.lang.ref.NativeReferenceQueue.remove(java.base@21.0.1/NativeReferenceQueue.java:89)
- locked <0x00000000e1f01670> (a java.lang.ref.NativeReferenceQueue$Lock)
at java.lang.ref.Finalizer$FinalizerThread.run(java.base@21.0.1/Finalizer.java:173)
"Signal Dispatcher" #11 [3756] daemon prio=9 os_prio=0 cpu=0.70ms elapsed=549.96s tid=0x00007fe8340b1110 nid=3756 waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"Service Thread" #12 [3757] daemon prio=9 os_prio=0 cpu=0.18ms elapsed=549.96s tid=0x00007fe8340b2750 nid=3757 runnable [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"Monitor Deflation Thread" #13 [3758] daemon prio=9 os_prio=0 cpu=161.02ms elapsed=549.96s tid=0x00007fe8340b3cf0 nid=3758 runnable [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"C2 CompilerThread0" #14 [3759] daemon prio=9 os_prio=0 cpu=81.61ms elapsed=549.96s tid=0x00007fe8340b5830 nid=3759 waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
No compile task
"C1 CompilerThread0" #15 [3760] daemon prio=9 os_prio=0 cpu=126.57ms elapsed=549.96s tid=0x00007fe8340b6ef0 nid=3760 waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
No compile task
"Notification Thread" #16 [3761] daemon prio=9 os_prio=0 cpu=0.21ms elapsed=549.95s tid=0x00007fe8340c5100 nid=3761 runnable [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"Common-Cleaner" #17 [3762] daemon prio=8 os_prio=0 cpu=2.68ms elapsed=549.94s tid=0x00007fe8340c8a50 nid=3762 waiting on condition [0x00007fe80d30e000]
java.lang.Thread.State: TIMED_WAITING (parking)
at jdk.internal.misc.Unsafe.park(java.base@21.0.1/Native Method)
- parking to wait for <0x00000000e1f10390> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
at java.util.concurrent.locks.LockSupport.parkNanos(java.base@21.0.1/LockSupport.java:269)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(java.base@21.0.1/AbstractQueuedSynchronizer.java:1847)
at java.lang.ref.ReferenceQueue.await(java.base@21.0.1/ReferenceQueue.java:71)
at java.lang.ref.ReferenceQueue.remove0(java.base@21.0.1/ReferenceQueue.java:143)
at java.lang.ref.ReferenceQueue.remove(java.base@21.0.1/ReferenceQueue.java:218)
at jdk.internal.ref.CleanerImpl.run(java.base@21.0.1/CleanerImpl.java:140)
at java.lang.Thread.runWith(java.base@21.0.1/Thread.java:1596)
at java.lang.Thread.run(java.base@21.0.1/Thread.java:1583)
at jdk.internal.misc.InnocuousThread.run(java.base@21.0.1/InnocuousThread.java:186)
"idle-timeout-task" #18 [3763] daemon prio=5 os_prio=0 cpu=9.68ms elapsed=549.87s tid=0x00007fe8340fa8f0 nid=3763 in Object.wait() [0x00007fe80d20e000]
java.lang.Thread.State: TIMED_WAITING (on object monitor)
at java.lang.Object.wait0(java.base@21.0.1/Native Method)
- waiting on <0x00000000e1fa5fa0> (a java.util.TaskQueue)
at java.lang.Object.wait(java.base@21.0.1/Object.java:366)
at java.util.TimerThread.mainLoop(java.base@21.0.1/Timer.java:563)
- locked <0x00000000e1fa5fa0> (a java.util.TaskQueue)
at java.util.TimerThread.run(java.base@21.0.1/Timer.java:516)
"HTTP-Dispatcher" #19 [3764] prio=5 os_prio=0 cpu=89.43ms elapsed=549.84s tid=0x00007fe83410aa70 nid=3764 runnable [0x00007fe80d10e000]
java.lang.Thread.State: RUNNABLE
at sun.nio.ch.EPoll.wait(java.base@21.0.1/Native Method)
at sun.nio.ch.EPollSelectorImpl.doSelect(java.base@21.0.1/EPollSelectorImpl.java:121)
at sun.nio.ch.SelectorImpl.lockAndDoSelect(java.base@21.0.1/SelectorImpl.java:130)
- locked <0x00000000e1fa3308> (a sun.nio.ch.Util$2)
- locked <0x00000000e1fa2f80> (a sun.nio.ch.EPollSelectorImpl)
at sun.nio.ch.SelectorImpl.select(java.base@21.0.1/SelectorImpl.java:142)
at sun.net.httpserver.ServerImpl$Dispatcher.run(jdk.httpserver@21.0.1/ServerImpl.java:474)
at java.lang.Thread.runWith(java.base@21.0.1/Thread.java:1596)
at java.lang.Thread.run(java.base@21.0.1/Thread.java:1583)
"DestroyJavaVM" #20 [3746] prio=5 os_prio=0 cpu=172.46ms elapsed=549.80s tid=0x00007fe8340162d0 nid=3746 waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"Attach Listener" #21 [3775] daemon prio=9 os_prio=0 cpu=39.40ms elapsed=260.89s tid=0x00007fe7a4000fe0 nid=3775 waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"VM Thread" os_prio=0 cpu=43.51ms elapsed=549.97s tid=0x00007fe8340a0e10 nid=3753 runnable
"GC Thread#0" os_prio=0 cpu=0.34ms elapsed=550.01s tid=0x00007fe834042490 nid=3747 runnable
"G1 Main Marker" os_prio=0 cpu=0.30ms elapsed=550.01s tid=0x00007fe834047a50 nid=3748 runnable
"G1 Conc#0" os_prio=0 cpu=0.19ms elapsed=550.01s tid=0x00007fe8340489f0 nid=3749 runnable
"G1 Refine#0" os_prio=0 cpu=0.24ms elapsed=550.01s tid=0x00007fe83406ccc0 nid=3750 runnable
"G1 Service" os_prio=0 cpu=42.37ms elapsed=550.01s tid=0x00007fe83406dc70 nid=3751 runnable
"VM Periodic Task Thread" os_prio=0 cpu=865.36ms elapsed=549.98s tid=0x00007fe834086b50 nid=3752 waiting on condition
JNI global refs: 12, weak refs: 0
pidã®äœçœ®ã¯å€ãããŸãããjattach [pid] jcmd Thread.printã§ãOKã§ãã
$ ./jattach 3745 jcmd Thread.print
Connected to remote JVM
JVM response code = 0
2024-02-18 15:51:35
Full thread dump OpenJDK 64-Bit Server VM (21.0.1+12-Ubuntu-222.04 mixed mode, sharing):
Threads class SMR info:
_java_thread_list=0x00007fe7a40024f0, length=13, elements={
0x00007fe8340ae000, 0x00007fe8340af680, 0x00007fe8340b1110, 0x00007fe8340b2750,
0x00007fe8340b3cf0, 0x00007fe8340b5830, 0x00007fe8340b6ef0, 0x00007fe8340c5100,
0x00007fe8340c8a50, 0x00007fe8340fa8f0, 0x00007fe83410aa70, 0x00007fe8340162d0,
0x00007fe7a4000fe0
}
"Reference Handler" #9 [3754] daemon prio=10 os_prio=0 cpu=0.49ms elapsed=604.39s tid=0x00007fe8340ae000 nid=3754 waiting on condition [0x00007fe80db0e000]
java.lang.Thread.State: RUNNABLE
at java.lang.ref.Reference.waitForReferencePendingList(java.base@21.0.1/Native Method)
at java.lang.ref.Reference.processPendingReferences(java.base@21.0.1/Reference.java:246)
at java.lang.ref.Reference$ReferenceHandler.run(java.base@21.0.1/Reference.java:208)
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JNI global refs: 12, weak refs: 0
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$ ./jattach 3745 jcmd Thread.dump_to_file -format=json thread_dump.json Connected to remote JVM JVM response code = 0 Created $HOME/thread_dump.json
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$ head -n 10 thread_dump.json
{
"threadDump": {
"processId": "3745",
"time": "2024-02-18T06:55:01.331346937Z",
"runtimeVersion": "21.0.1+12-Ubuntu-222.04",
"threadContainers": [
{
"container": "<root>",
"parent": null,
"owner": null,
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## 3805ã¯Java 17ã§åäœãããŠããããã°ã©ã ã®pid $ ./jattach 3805 jcmd Thread.dump_to_file -format=json thread_dump.json Connected to remote JVM JVM response code = -1 java.lang.IllegalArgumentException: Unknown diagnostic command
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$ ./jattach 3840 jcmd Connected to remote JVM JVM response code = 0
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## Java 8
$ /usr/lib/jvm/java-8-openjdk-amd64/bin/java -Xmx512M -Dtarget.port=8080 Server
[2024-02-18T16:02:21.863] start lightweight http server.
$ ./jattach 3866 properties | grep '^java.*version'
java.vm.version=25.392-b08
java.runtime.version=1.8.0_392-8u392-ga-1~22.04-b08
java.class.version=52.0
java.specification.version=1.8
java.vm.specification.version=1.8
java.version=1.8.0_392
java.specification.maintenance.version=5
$ ./jattach 3866 threaddump | head
Connected to remote JVM
JVM response code = 0
2024-02-18 16:03:27
Full thread dump OpenJDK 64-Bit Server VM (25.392-b08 mixed mode):
"Attach Listener" #12 daemon prio=9 os_prio=0 tid=0x00007f0e48001000 nid=0xf2b waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
"DestroyJavaVM" #11 prio=5 os_prio=0 tid=0x00007f0e7400a000 nid=0xf1b waiting on condition [0x0000000000000000]
java.lang.Thread.State: RUNNABLE
## Java 11
$ /usr/lib/jvm/java-11-openjdk-amd64/bin/java -Xmx512M -Dtarget.port=8080 Server
[2024-02-18T16:03:49.186818] start lightweight http server.
$ ./jattach 3893 properties | grep '^java.*version'
java.specification.version=11
java.vm.specification.version=11
java.version.date=2023-10-17
java.runtime.version=11.0.21+9-post-Ubuntu-0ubuntu122.04
java.version=11.0.21
java.vm.version=11.0.21+9-post-Ubuntu-0ubuntu122.04
java.specification.maintenance.version=2
java.class.version=55.0
$ ./jattach 3893 threaddump | head
Connected to remote JVM
JVM response code = 0
2024-02-18 16:04:07
Full thread dump OpenJDK 64-Bit Server VM (11.0.21+9-post-Ubuntu-0ubuntu122.04 mixed mode, sharing):
Threads class SMR info:
_java_thread_list=0x00007fab1c000c40, length=12, elements={
0x00007fab60092000, 0x00007fab60094000, 0x00007fab60099800, 0x00007fab6009b800,
0x00007fab6009d800, 0x00007fab6009f800, 0x00007fab600a1800, 0x00007fab600d5000,
0x00007fab600fb000, 0x00007fab6016b800, 0x00007fab60015000, 0x00007fab1c001000
## Java 17
$ /usr/lib/jvm/java-17-openjdk-amd64/bin/java -Xmx512M -Dtarget.port=8080 Server
[2024-02-18T16:04:35.788345626] start lightweight http server.
$ ./jattach 3920 properties | grep '^java.*version'
java.specification.version=17
java.vm.specification.version=17
java.version.date=2023-10-17
java.runtime.version=17.0.9+9-Ubuntu-122.04
java.version=17.0.9
java.vm.version=17.0.9+9-Ubuntu-122.04
java.class.version=61.0
$ ./jattach 3920 threaddump | head
Connected to remote JVM
JVM response code = 0
2024-02-18 16:04:55
Full thread dump OpenJDK 64-Bit Server VM (17.0.9+9-Ubuntu-122.04 mixed mode, sharing):
Threads class SMR info:
_java_thread_list=0x00007f7a58001e40, length=14, elements={
0x00007f7ae408fe30, 0x00007f7ae4091220, 0x00007f7ae40967c0, 0x00007f7ae4097b80,
0x00007f7ae4098fa0, 0x00007f7ae409a960, 0x00007f7ae409bea0, 0x00007f7ae409d320,
0x00007f7ae40aca40, 0x00007f7ae40b0080, 0x00007f7ae40d6a60, 0x00007f7ae40e3ed0,
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https://github.com/jattach/jattach/blob/v2.2/src/posix/jattach_hotspot.c
https://github.com/jattach/jattach/blob/v2.2/src/posix/jattach_openj9.c
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int jattach_hotspot(int pid, int nspid, int argc, char** argv, int print_output) { if (check_socket(nspid) != 0 && start_attach_mechanism(pid, nspid) != 0) { perror("Could not start attach mechanism"); return 1; } int fd = connect_socket(nspid); if (fd == -1) { perror("Could not connect to socket"); return 1; } if (print_output) { printf("Connected to remote JVM\n"); } if (write_command(fd, argc, argv) != 0) { perror("Error writing to socket"); close(fd); return 1; } int result = read_response(fd, argc, argv, print_output); close(fd); return result; }
https://github.com/jattach/jattach/blob/v2.2/src/posix/jattach_hotspot.c#L178-L204
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// Connect to UNIX domain socket created by JVM for Dynamic Attach static int connect_socket(int pid) { int fd = socket(PF_UNIX, SOCK_STREAM, 0); if (fd == -1) { return -1; } struct sockaddr_un addr; addr.sun_family = AF_UNIX; int bytes = snprintf(addr.sun_path, sizeof(addr.sun_path), "%s/.java_pid%d", tmp_path, pid); if (bytes >= sizeof(addr.sun_path)) { addr.sun_path[sizeof(addr.sun_path) - 1] = 0; } if (connect(fd, (struct sockaddr*)&addr, sizeof(addr)) == -1) { close(fd); return -1; } return fd; }
https://github.com/jattach/jattach/blob/v2.2/src/posix/jattach_hotspot.c#L83-L103
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// Send command with arguments to socket static int write_command(int fd, int argc, char** argv) { char buf[8192]; const char* const limit = buf + sizeof(buf); // jcmd has 2 arguments maximum; merge excessive arguments into one int cmd_args = argc >= 2 && strcmp(argv[0], "jcmd") == 0 ? 2 : argc >= 4 ? 4 : argc; // Protocol version char* p = stpncpy(buf, "1", sizeof(buf)) + 1; int i; for (i = 0; i < argc && p < limit; i++) { if (i >= cmd_args) p[-1] = ' '; p = stpncpy(p, argv[i], limit - p) + 1; } for (i = cmd_args; i < 4 && p < limit; i++) { *p++ = 0; } const char* q = p < limit ? p : limit; for (p = buf; p < q; ) { ssize_t bytes = write(fd, p, q - p); if (bytes <= 0) { return -1; } p += (size_t)bytes; } return 0; }
https://github.com/jattach/jattach/blob/v2.2/src/posix/jattach_hotspot.c#L105-L134
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// Mirror response from remote JVM to stdout static int read_response(int fd, int argc, char** argv, int print_output) { char buf[8192]; ssize_t bytes = read(fd, buf, sizeof(buf) - 1); if (bytes == 0) { fprintf(stderr, "Unexpected EOF reading response\n"); return 1; } else if (bytes < 0) { perror("Error reading response"); return 1; } // First line of response is the command result code buf[bytes] = 0; int result = atoi(buf); // Special treatment of 'load' command if (result == 0 && argc > 0 && strcmp(argv[0], "load") == 0) { size_t total = bytes; while (total < sizeof(buf) - 1 && (bytes = read(fd, buf + total, sizeof(buf) - 1 - total)) > 0) { total += (size_t)bytes; } bytes = total; // The second line is the result of 'load' command; since JDK 9 it starts from "return code: " buf[bytes] = 0; result = atoi(strncmp(buf + 2, "return code: ", 13) == 0 ? buf + 15 : buf + 2); } if (print_output) { // Mirror JVM response to stdout printf("JVM response code = "); do { fwrite(buf, 1, bytes, stdout); bytes = read(fd, buf, sizeof(buf)); } while (bytes > 0); printf("\n"); } return result; }
https://github.com/jattach/jattach/blob/v2.2/src/posix/jattach_hotspot.c#L136-L176
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