RFR: 8176717: GC log file handle leaked to child processes (original) (raw)

Leo Korinth leo.korinth at oracle.com
Mon Mar 12 13:20:13 UTC 2018

Hi,

This fix is for all operating systems though the problem only seams to appear on windows.

I am creating a proxy function for fopen (os::fopen_retain) that appends the non-standard "e" mode for linux and bsds. For windows the "N" mode is used. For other operating systems, I assume that I can use fcntl F_SETFD FD_CLOEXEC. I think this will work for AIX, Solaris and other operating systems that do not support the "e" flag. Feedback otherwise please!

The reason that I use the mode "e" and not only fcntl for linux and bsds is threefold. First, I still need to use mode flags on windows as it does not support fcntl. Second, I probably save a system call. Third, the change will be applied directly, and there will be no point in time (between system calls) when the process can leak the file descriptor, so it is safer.

The test case forks three VMs in a row. By doing so we know that the second VM is opened with a specific log file. The third VM should have less open file descriptors (as it is does not use logging) which is checked using a UnixOperatingSystemMXBean. This is not possible on windows, so on windows I try to rename the file, which will not work if the file is opened (the actual reason the bug was opened).

The added test case shows that the bug fix closes the log file on windows. The VM on other operating systems closed the log file even before the fix.

Maybe the test case should be moved to a different path?

Bug: https://bugs.openjdk.java.net/browse/JDK-8176717 https://bugs.openjdk.java.net/browse/JDK-8176809

Webrev: http://cr.openjdk.java.net/~lkorinth/8176717/00/

Testing: hs-tier1, hs-tier2 and TestInheritFD.java (on 64-bit linux, solaris, windows and mac)

Thanks, Leo

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