执行Runtime.exec异常: error=12,Cannot allocate memory

Exception Trace：

In the Linux circumstance, when the program executes till this place:
Process p = Runtime.getRuntime().exec(cmdArr);
it throws an exception like this：
java.io.IOException: Cannot run program "/opt/X.sh": java.io.IOException: error=12, Cannot allocate memory

        at java.lang.ProcessBuilder.start(ProcessBuilder.java:474)

        at java.lang.Runtime.exec(Runtime.java:610)

        at java.lang.Runtime.exec(Runtime.java:448)

        at java.lang.Runtime.exec(Runtime.java:345)

        ...

Caused by: java.io.IOException: java.io.IOException: error=12, Cannot allocate memory

        at java.lang.UNIXProcess.<init>(UNIXProcess.java:164)

        at java.lang.ProcessImpl.start(ProcessImpl.java:81)

        at java.lang.ProcessBuilder.start(ProcessBuilder.java:467)

        ... 4 more

These are the status and environment for it:

Top：   PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND 16405 root      19   0 6484m 5.1g  10m S  101 86.7   4:09.11 java Free：              total       used       free     shared    buffers     cached Mem:       6108084    5616532     491552                 2244     185100 -/+ buffers/cache:    5429188     678896 Swap:      2104472      12584    2091888

As shown before, the program has hold about 87% memory. When the memory usage is low, there is no exception throwed. It could be why java program fails to process “Runtime.exec()”.

 

 The Official Explains：

Bug ID: 5049299 Votes 45 Synopsis (process) Use posix_spawn, not fork, on S10 to avoid swap exhaustion Category java:classes_lang Reported Against 5.0 , b06 , 1.4.2_04 Release Fixed   State 6-Fix Understood, request for enhancement Priority: 2-High Related Bugs 6381152 , 6605835 , 6728616 , 6745199 , 6845504 , 6850720 , 4343908 , 4391042 Submit Date 18-MAY-2004 Description If you run a "small" program (e.g., a Perl script) from a "big" Java process on a machine with "moderate" free swap space (but not as much as the big Java process), then Runtime.exec() fails.

http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=5049299

 

 Cause Detail:

This issue dues to the operating mechanism of “Runtime.exec” in Java.

In Java program, “ProcessBuilder.start” and “Runtime.exec” use fork() on *NIX system, which allocates the child process the same amount of memory as the parent process. This will double the used memory for a short time. So when the Java main process has used over 50% memory, it will absolutely never launch a child process using “Runtime.exec” successful, even the process needs almost no memory.

Solutions:

There are three workable solutions:

1. The middleware of Tanuki may solve this problem. The question is, it is complicated and also expensive.

    See-  http://wrapper.tanukisoftware.com/doc/english/child-exec.html

2. Separate the process using “Runtime.exec” from the main process into a new java process. So when the “Runtime.exec” is called ,it will only double the memory of the new process, using almost no memory.

which means:

    a. When start/stop the main process, the “Runtime.exec” process should be started/stopped at the same time.

    b. Add an independent socket in the main process to communicate with the new process. The exec command will be delivered to the new process to execute.

This will surely increase the complexity and maintenance of the system.

 

3. Update JDK1.6 to JDK1.7

This bug is fixed in JDK1.7 ,using new invoking mechanism of external program.

(Pipes be tested in JDK snapshot release: build 1.7.0-b147,passed with no exceptions; it also reduced the memory usage for about 20%)

This will need no modification for current source code.