为什么会有不同数量的线程？
为什么会有不同数量的线程？
提问于 2018-10-19 06:07:49
我的scala程序的一部分：
import java.util.concurrent.{ExecutorService, Executors, TimeUnit}
val genericExecutorService = Executors.newCachedThreadPool()
val scheduledExecutorService = Executors.newScheduledThreadPool(4)
val scheduledExecutorService1 = Executors.newScheduledThreadPool(1)
val scheduledExecutorService2 = Executors.newScheduledThreadPool(1)我计算了日志文件中的线程数，结果是120。日志文件的一部分：
2018-10-18 00:00:00,421 INFO [pool-7-thread-32] xxx统计日志文件中的线程数：
$ grep -r "thread" xxx.log | grep -Po '(?<=(\[)).*(?=\])' | sort | uniq -c | wc -l
120我将java的线程数如下：
$ cat /proc/2966/status | grep Threads
Threads: 1524
$ ps -eLF| grep -c java
1525
$ ps -L -o pid= -p 2966 | wc -l
1524为什么1525和120如此不同？欢迎任何提示。谢谢。
回答 1
Stack Overflow用户
发布于 2018-10-19 06:28:10
您可以使用更好的工具来分析JVM应用程序中的线程，而不是依赖于日志记录。有像jmc和jconsole这样的可视化工具。如果您在生产机器上，可能无法使用可视化工具，则会出现jstack。
如果我跟踪了JVM应用程序，则为。
object Testing {
def main(args: Array[String]): Unit = {
import java.util.concurrent.{ExecutorService, Executors, TimeUnit}
val genericExecutorService = Executors.newCachedThreadPool()
val scheduledExecutorService = Executors.newScheduledThreadPool(4)
val scheduledExecutorService1 = Executors.newScheduledThreadPool(1)
val scheduledExecutorService2 = Executors.newScheduledThreadPool(1)
genericExecutorService.execute(() => {
println("0")
})
scheduledExecutorService.execute(() => {
println("1")
})
scheduledExecutorService1.execute(() => {
println("2")
})
scheduledExecutorService2.execute(() => {
println("3")
})
}
}我可以使用jstack 获取线程，使用该应用程序的proccessId，
$ jstack 68209 | grep thread
Full thread dump Java HotSpot(TM) 64-Bit Server VM (25.151-b12 mixed mode):
"pool-4-thread-1" #14 prio=5 os_prio=31 tid=0x00007ff1b812a800 nid=0xa503 waiting on condition [0x000070000c305000]
"pool-3-thread-1" #13 prio=5 os_prio=31 tid=0x00007ff1b812a000 nid=0xa703 waiting on condition [0x000070000c202000]
"pool-2-thread-1" #12 prio=5 os_prio=31 tid=0x00007ff1b80f9000 nid=0xa903 waiting on condition [0x000070000c0ff000]
"pool-1-thread-1" #11 prio=5 os_prio=31 tid=0x00007ff1b9869800 nid=0x5803 waiting on condition [0x000070000bffc000]
"GC task thread#0 (ParallelGC)" os_prio=31 tid=0x00007ff1b9802800 nid=0x1c07 runnable
"GC task thread#1 (ParallelGC)" os_prio=31 tid=0x00007ff1b9001000 nid=0x1d03 runnable
"GC task thread#2 (ParallelGC)" os_prio=31 tid=0x00007ff1ba804800 nid=0x2b03 runnable
"GC task thread#3 (ParallelGC)" os_prio=31 tid=0x00007ff1ba805000 nid=0x5303 runnable
"GC task thread#4 (ParallelGC)" os_prio=31 tid=0x00007ff1ba805800 nid=0x5103 runnable
"GC task thread#5 (ParallelGC)" os_prio=31 tid=0x00007ff1b8810800 nid=0x2c03 runnable
"GC task thread#6 (ParallelGC)" os_prio=31 tid=0x00007ff1b981e800 nid=0x4e03 runnable
"GC task thread#7 (ParallelGC)" os_prio=31 tid=0x00007ff1b981f000 nid=0x4c03 runnable 你也可以简单地做jstack pid，但这会产生一个完整的线程转储，包括thread_state等等。
使用 jmc 可视化工具的
可能会有帮助：Monitoring queue of ExecutionContextExecutor “scala.concurrent.ExecutionContext.Implicits.global”
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/52883277
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