Java 进程没有响应，但在我使用 jstack -F 执行线程转储后恢复

Question

我有一个 Java 进程卡住(每天一次/两次)的奇怪问题，它只会在我执行后恢复:

jstack -F ${PID}

当 Java 进程卡住时，如果我尝试使用 jcmd 进行线程转储，我会收到 AttachNotSupportedException。

我只设法使用 jstack -F 进行线程转储，并使用与 JRE 版本同步的 JDK 版本，JRE 版本用于启动 java 进程。

我唯一能想到的是，也许 OS 调度程序不允许 Java 进程使用 CPU 时间，如果我执行 jstack -F 我强制它允许它运行？

我们将不胜感激任何反馈。

问候，

克里斯蒂

UPDATE-1

今天又发生了。我检查的第一件事是那个盒子上使用的内存 (99.1%)。之后，我执行了一个 jmap -heap，并且在堆转储后没有任何问题地恢复了进程。附加堆转储。

jmap -heap 7703
Attaching to process ID 7703, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 25.162-b12

using thread-local object allocation.
Parallel GC with 2 thread(s)

Heap Configuration:
   MinHeapFreeRatio         = 0
   MaxHeapFreeRatio         = 100
   MaxHeapSize              = 536870912 (512.0MB)
   NewSize                  = 89128960 (85.0MB)
   MaxNewSize               = 178782208 (170.5MB)
   OldSize                  = 179306496 (171.0MB)
   NewRatio                 = 2
   SurvivorRatio            = 8
   MetaspaceSize            = 21807104 (20.796875MB)
   CompressedClassSpaceSize = 1073741824 (1024.0MB)
   MaxMetaspaceSize         = 17592186044415 MB
   G1HeapRegionSize         = 0 (0.0MB)

Heap Usage:
PS Young Generation
Eden Space:
   capacity = 143130624 (136.5MB)
   used     = 73244792 (69.85167694091797MB)
   free     = 69885832 (66.64832305908203MB)
   51.1733897003062% used
From Space:
   capacity = 17825792 (17.0MB)
   used     = 8176960 (7.79815673828125MB)
   free     = 9648832 (9.20184326171875MB)
   45.871510225183826% used
To Space:
   capacity = 17825792 (17.0MB)
   used     = 0 (0.0MB)
   free     = 17825792 (17.0MB)
   0.0% used
PS Old Generation
   capacity = 243269632 (232.0MB)
   used     = 23534032 (22.443801879882812MB)
   free     = 219735600 (209.5561981201172MB)
   9.674052534432247% used

25964 interned Strings occupying 2759784 bytes.

UPDATE-2

启用 GC 日志后，当进程卡住时，这是 GC 日志的尾部。

2020-09-02T06:51:11.286+0000: 86020.549: Total time for which application 

threads were stopped: 0.0001978 seconds, Stopping threads took: 0.0000666 seconds
2020-09-02T06:51:11.286+0000: 86020.550: Application time: 0.0000610 seconds
2020-09-02T06:51:11.286+0000: 86020.550: Total time for which application threads were stopped: 0.0001793 seconds, Stopping threads took: 0.0000589 seconds
2020-09-02T06:51:11.287+0000: 86020.550: Application time: 0.0003371 seconds
2020-09-02T06:51:11.287+0000: 86020.550: Total time for which application threads were stopped: 0.0001749 seconds, Stopping threads took: 0.0000283 seconds
2020-09-02T06:51:11.287+0000: 86020.550: Application time: 0.0001277 seconds
2020-09-02T06:51:11.287+0000: 86020.550: Total time for which application threads were stopped: 0.0001554 seconds, Stopping threads took: 0.0000364 seconds
2020-09-02T06:51:11.287+0000: 86020.551: Application time: 0.0000400 seconds
2020-09-02T06:51:11.287+0000: 86020.551: Total time for which application threads were stopped: 0.0001082 seconds, Stopping threads took: 0.0000158 seconds
2020-09-02T06:51:11.288+0000: 86020.552: Application time: 0.0010649 seconds
2020-09-02T06:51:11.288+0000: 86020.552: Total time for which application threads were stopped: 0.0001945 seconds, Stopping threads took: 0.0000571 seconds
2020-09-02T06:51:11.289+0000: 86020.552: Application time: 0.0001078 seconds
2020-09-02T06:51:11.289+0000: 86020.552: Total time for which application threads were stopped: 0.0001852 seconds, Stopping threads took: 0.0000336 seconds
2020-09-02T06:51:11.289+0000: 86020.552: Application time: 0.0000366 seconds
2020-09-02T06:51:11.289+0000: 86020.552: Total time for which application threads were stopped: 0.0000910 seconds, Stopping threads took: 0.0000180 seconds
2020-09-02T06:51:11.289+0000: 86020.552: Application time: 0.0000412 seconds
2020-09-02T06:51:11.289+0000: 86020.553: Total time for which application threads were

Answer 1

如果在使用 jcmd 获取线程转储时收到 AttachNotSupportedException，请尝试在运行 java 进程的同一用户下运行 jcmd。 参见 com.sun.tools.attach.AttachNotSupportedException: Unable to open socket file: target process not responding or HotSpot VM not loaded