[jira] Closed: (HARMONY-5485) [classlib][luni] Runtime.exec hangs on out-of-file-handles

["Mark Hindess (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HARMONY-5485?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Mark Hindess closed HARMONY-5485.
---------------------------------

    Resolution: Fixed

Fixed in r620494.

> [classlib][luni] Runtime.exec hangs on out-of-file-handles
> ----------------------------------------------------------
>
>                 Key: HARMONY-5485
>                 URL: https://issues.apache.org/jira/browse/HARMONY-5485
>             Project: Harmony
>          Issue Type: Bug
>          Components: Classlib
>         Environment: Unix
>            Reporter: Mark Hindess
>            Assignee: Mark Hindess
>            Priority: Minor
>
> Runtime.exec (in unix/procimpl.c) creates 5 pipes - 10 file handles - with no error checking.  If you run as simple test case such as:
> import java.lang.Runtime;
> import java.io.IOException;
> public class FileHandleHang {
>     public static void main(String[] args) throws IOException {
>         Runtime.getRuntime().exec("no-such-program");
>     }
> }
> using "strace -q -f -e pipe java FileHandleHang" and look for the pipe creates which will be
> something like:
> [pid  6841] pipe([50, 51])              = 0
> [pid  6841] pipe([52, 53])              = 0
> [pid  6841] pipe([54, 55])              = 0
> [pid  6841] pipe([56, 57])              = 0
> [pid  6841] pipe([58, 59])              = 0
> then limit the number of file handles with "ulimit -n 56" and re-run the test then it hangs.  The strace output would be something like:
> [pid  6853] pipe([50, 51])              = 0
> [pid  6853] pipe([52, 53])              = 0
> [pid  6853] pipe([54, 55])              = 0
> [pid  6853] pipe(0x40167760)            = -1 EMFILE (Too many open files)
> [pid  6853] pipe(0x40167770)            = -1 EMFILE (Too many open files)
> There really needs to be error checking on all of these pipe calls to fix this and related problems.
> I noticed this problem because recent gcc with -Wall complains about these calls with the following warning:
>   ignoring return value of 'pipe', declared with attribute warn_unused_result

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