* David Lloyd:
> Pipe communication isn't very costly AFAIK. The added complexity
> would be waiting for either a thing to appear on the pipe indicating
> success or else a waitpid/waitid+WNOHANG for exit code 127. But
> writing a thing to the pipe won't help determine if the subsequent
> exec succeeded, which is really the interesting bit.
Please have a look at the code. It's already using CLOEXEC to cover
the execve call (src/java.base/unix/native/libjava/ProcessImpl_md.c):
switch (readFully(fail[0], &errnum, sizeof(errnum))) {
case 0: break; /* Exec succeeded */
case sizeof(errnum):
waitpid(resultPid, NULL, 0);
throwIOException(env, errnum, "Exec failed");
goto Catch;
default:
throwIOException(env, errno, "Read failed");
goto Catch;
}
Instead of 0/4 bytes, the outcome could be 0/4/8 bytes, corresponding to
jspawnhelper exec failure, complete success, and exec failure in
jspawnhelper.
The run-time cost would be the additional pipe write in jspawnhelper.
There shouldn't even be another ping-pong between the processes.
Thanks,
Florian
