Replacing syscall(_NR_fork) on linux with syscall(_NR_clone)
david.holmes at oracle.com
Fri Apr 10 07:47:14 UTC 2015
In os::fork_and_exec we provide a per platform fork/exec implementation
for use by the OnError and OnOutOfMemory JVM options.
On linux this is implemented with direct syscalls to _NR_fork (sys_fork)
We already encountered a problem on linux-sparc:
due to a different register usage for the return value, which is so far
restricted to the 7u train but will need addressing in 8u and 9.
Further it seems that the fork syscall has actually been deprecated for
quite some time and we are now seeing kernels on some platforms which
are no longer providing any of the deprecated syscalls - we simply get
an error ENOSYS.
The fork() library was updated to use clone a long time ago, but as I
understand it we can't use the fork() library call because we might be
executing in a signal-handling context within the error handler.
So I'm considering switching to use the clone syscall for all linux systems.
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