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Dynamic deadpool poll time for faster exit detection on linux #148

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Dynamic deadpool poll time for faster exit detection on linux #148

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22 changes: 12 additions & 10 deletions src/main/java/com/zaxxer/nuprocess/linux/ProcessEpoll.java
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Original file line number Diff line number Diff line change
Expand Up @@ -40,6 +40,9 @@ class ProcessEpoll extends BaseEventProcessor<LinuxProcess>
private final EpollEvent triggeredEvent;
private final List<LinuxProcess> deadPool;

// see comment in #cleanupProcess for explanation on dynamicDeadpoolPollInterval
private int dynamicDeadpoolPollInterval = DEADPOOL_POLL_INTERVAL;

private LinuxProcess process;

ProcessEpoll()
Expand Down Expand Up @@ -191,7 +194,9 @@ public boolean process()
int stderrFd = Integer.MIN_VALUE;
LinuxProcess linuxProcess = null;
try {
int nev = LibEpoll.epoll_wait(epoll, triggeredEvent.getPointer(), 1, DEADPOOL_POLL_INTERVAL);
int nev = LibEpoll.epoll_wait(epoll, triggeredEvent.getPointer(), 1, dynamicDeadpoolPollInterval);
// see comment in #cleanupProcess for explanation on dynamicDeadpoolPollInterval
dynamicDeadpoolPollInterval = Math.min(DEADPOOL_POLL_INTERVAL, 2 * dynamicDeadpoolPollInterval);
if (nev == -1) {
int errno = Native.getLastError();
if (errno == LibC.EINTR) {
Expand Down Expand Up @@ -292,20 +297,17 @@ protected void close()

private void cleanupProcess(LinuxProcess linuxProcess, int stdinFd, int stdoutFd, int stderrFd)
{
// we detected a close of a stream, this means that the process is going to be closed soon or is already closed
// in the absence of other EPoll events this means that we might wait for the full DEADPOOL_POLL_INTERVAL
// before we do waitpid check again. With dynamic poll interval, we check again in the intervals of
// 1, 2, 4, 8, ... DEADPOOL_POLL_INTERVAL ms. This allows us to catch exit much sooner.
dynamicDeadpoolPollInterval = 1;

pidToProcessMap.remove(linuxProcess.getPid());
fildesToProcessMap.remove(stdinFd);
fildesToProcessMap.remove(stdoutFd);
fildesToProcessMap.remove(stderrFd);

// linuxProcess.close(linuxProcess.getStdin());
// linuxProcess.close(linuxProcess.getStdout());
// linuxProcess.close(linuxProcess.getStderr());

if (linuxProcess.cleanlyExitedBeforeProcess.get()) {
linuxProcess.onExit(0);
return;
}

IntByReference ret = new IntByReference();
int rc = LibC.waitpid(linuxProcess.getPid(), ret, LibC.WNOHANG);

Expand Down