Question

我现在正在调试一个程序，每个外部进程有两个线程，这两个线程继续使用while ((i = in.read(buf, 0, buf.length)) >= 0)循环读取Process.getErrorStream（）和Process.getInputStream（）。

有时当外部进程因JVM崩溃而崩溃时（请参阅these hs_err_pid.log files），那些读取该外部进程的stdout / stderr的线程开始消耗100％的CPU并且永不退出。 循环体未被执行（我在那里添加了一个日志语句），因此无限循环似乎位于本机方法java.io.FileInputStream.readBytes内。

我在Windows 7 64位（jdk1.6.0_30 64位，jdk1.7.0_03 64位）和Linux 2.6.18（jdk1.6.0_21 32位）上都重现了这一点。相关代码为here，并使用like this。请参阅这些链接以获取完整代码 - 以下是有趣的内容：

private final byte[]              buf = new byte[256];
private final InputStream         in;
...    

int i;
while ((i = this.in.read(this.buf, 0, this.buf.length)) >= 0) {
    ...
}

堆栈跟踪看起来像

"PIT Stream Monitor" daemon prio=6 tid=0x0000000008869800 nid=0x1f70 runnable [0x000000000d7ff000]
   java.lang.Thread.State: RUNNABLE
    at java.io.FileInputStream.readBytes(Native Method)
    at java.io.FileInputStream.read(FileInputStream.java:220)
    at java.io.BufferedInputStream.fill(BufferedInputStream.java:218)
    at java.io.BufferedInputStream.read1(BufferedInputStream.java:258)
    at java.io.BufferedInputStream.read(BufferedInputStream.java:317)
    - locked <0x00000007c89d6d90> (a java.io.BufferedInputStream)
    at org.pitest.util.StreamMonitor.readFromStream(StreamMonitor.java:38)
    at org.pitest.util.StreamMonitor.process(StreamMonitor.java:32)
    at org.pitest.util.AbstractMonitor.run(AbstractMonitor.java:19)
   Locked ownable synchronizers:
    - None

或

"PIT Stream Monitor" daemon prio=6 tid=0x0000000008873000 nid=0x1cb8 runnable [0x000000000e3ff000]
   java.lang.Thread.State: RUNNABLE
    at java.io.FileInputStream.readBytes(Native Method)
    at java.io.FileInputStream.read(FileInputStream.java:220)
    at org.pitest.util.StreamMonitor.readFromStream(StreamMonitor.java:38)
    at org.pitest.util.StreamMonitor.process(StreamMonitor.java:32)
    at org.pitest.util.AbstractMonitor.run(AbstractMonitor.java:19)
   Locked ownable synchronizers:
    - None

使用Sysinternals Process Explorer，我能够获得这些线程的本机堆栈跟踪。大多数情况下，超过80％的时间，堆栈跟踪看起来像这样：

ntdll.dll!NtReadFile+0xa
KERNELBASE.dll!ReadFile+0x7a
kernel32.dll!ReadFile+0x59
java.dll!handleRead+0x2c
java.dll!VerifyClassCodesForMajorVersion+0x1d1
java.dll!Java_java_io_FileInputStream_readBytes+0x1d

这也经常发生：

ntdll.dll!RtlNtStatusToDosErrorNoTeb+0x52
ntdll.dll!RtlNtStatusToDosError+0x23
KERNELBASE.dll!GetCurrentThreadId+0x2c
KERNELBASE.dll!CreatePipe+0x21a
kernel32.dll!ReadFile+0x59
java.dll!handleRead+0x2c
java.dll!VerifyClassCodesForMajorVersion+0x1d1
java.dll!Java_java_io_FileInputStream_readBytes+0x1d

ntdll.dll!RtlNtStatusToDosErrorNoTeb+0x42
ntdll.dll!RtlNtStatusToDosError+0x23
KERNELBASE.dll!GetCurrentThreadId+0x2c
KERNELBASE.dll!CreatePipe+0x21a
kernel32.dll!ReadFile+0x59
java.dll!handleRead+0x2c
java.dll!VerifyClassCodesForMajorVersion+0x1d1
java.dll!Java_java_io_FileInputStream_readBytes+0x1d

有时它正在执行代码的这一部分：

java.dll!VerifyClassCodesForMajorVersion+0xc3
java.dll!Java_java_io_FileInputStream_readBytes+0x1d

java.dll!Java_sun_io_Win32ErrorMode_setErrorMode+0x847c
java.dll!VerifyClassCodesForMajorVersion+0xd7
java.dll!Java_java_io_FileInputStream_readBytes+0x1d

jvm.dll!JNI_GetCreatedJavaVMs+0x1829f
java.dll!VerifyClassCodesForMajorVersion+0x128
java.dll!Java_java_io_FileInputStream_readBytes+0x1d

jvm.dll+0x88c1
jvm.dll!JNI_GetCreatedJavaVMs+0x182a7
java.dll!VerifyClassCodesForMajorVersion+0x128
java.dll!Java_java_io_FileInputStream_readBytes+0x1d

java.dll!VerifyClassCodesForMajorVersion+0x10b
java.dll!Java_java_io_FileInputStream_readBytes+0x1d

jvm.dll!JNI_CreateJavaVM+0x1423
java.dll!VerifyClassCodesForMajorVersion+0x190
java.dll!Java_java_io_FileInputStream_readBytes+0x1d

jvm.dll+0x88bf
jvm.dll!JNI_CreateJavaVM+0x147d
java.dll!VerifyClassCodesForMajorVersion+0x190
java.dll!Java_java_io_FileInputStream_readBytes+0x1d

java.dll!VerifyClassCodesForMajorVersion+0x1aa
java.dll!Java_java_io_FileInputStream_readBytes+0x1d

java.dll!VerifyClassCodesForMajorVersion+0x1c3
java.dll!Java_java_io_FileInputStream_readBytes+0x1d

java.dll!VerifyClassCodesForMajorVersion+0x224
java.dll!Java_java_io_FileInputStream_readBytes+0x1d

任何想法如何解决这个问题？这是JVM的已知问题吗？有解决方法吗？

Answer 1

我还没有能够在本地重现这个，但两种可能的解决方法可能是

使用in.available()。
将外部进程中的 stout 和 stderr 重定向到套接字并请从控制过程中读取此内容。

java.io.FileInputStream.readBytes（本机方法）的无限100％CPU使用率

1 个答案: