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Cygwin: signal: Fix high load when retrying to process pending signal

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The commit e10f822a2b39 has a problem that CPU load gets high if
pending signal is not processed successfully for a long time.
With this patch, wait_sig() calls Sleep(1), rather than yield(),
if the pending signal has not been processed successfully for a
predetermined time to prevent CPU from high load.

Addresses: https://cygwin.com/pipermail/cygwin/2024-December/256884.html
Fixes: e10f822a2b39 ("Cygwin: signal: Handle queued signal without explicit __SIGFLUSH")
Reported-by: 凯夏 <walkerxk@gmail.com>
Reviewed-by: Corinna Vinschen <corinna@vinschen.de>
Signed-off-by: Takashi Yano <takashi.yano@nifty.ne.jp>
This commit is contained in:
Takashi Yano 2024-12-12 15:03:39 +09:00
parent 06952f41ff
commit 1d1451ccd2
1 changed files with 9 additions and 1 deletions
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10
winsup/cygwin/sigproc.cc
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@ -1345,6 +1345,12 @@ wait_sig (VOID *)
hntdll = GetModuleHandle ("ntdll.dll");
/* GetTickCount() here is enough because GetTickCount() - t0 does
not overflow until 49 days psss. Even if GetTickCount() overflows,
GetTickCount() - t0 returns correct value, since underflow in
unsigned wraps correctly. Pending a signal for more thtn 49
days would be noncense. */
DWORD t0 = GetTickCount ();
for (;;)
{
DWORD nb;
@ -1354,7 +1360,7 @@ wait_sig (VOID *)
else if (sigq.start.next
&& PeekNamedPipe (my_readsig, NULL, 0, NULL, &nb, NULL) && !nb)
{
yield ();
Sleep (GetTickCount () - t0 > 10 ? 1 : 0);
pack.si.si_signo = __SIGFLUSH;
}
else if (!ReadFile (my_readsig, &pack, sizeof (pack), &nb, NULL))
@ -1364,6 +1370,8 @@ wait_sig (VOID *)
system_printf ("garbled signal pipe data nb %u, sig %d", nb, pack.si.si_signo);
continue;
}
if (pack.si.si_signo != __SIGFLUSH)
t0 = GetTickCount ();
sigq.retry = false;
/* Don't process signals when we start exiting */