Hi,
We will probably have to introduce --enable-zend-signals configure
switch and disable zend signals by default. Or we will stuck with 5.4
release forever.
Thanks. Dmitry.
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Hi Arnaud and Lucas,
I can confirm the problem. Just start Apache with mod_php, generate some
load (e.g. ab -t 120 http://.../hello.php), then run 'apachectl restart'
for few times, then 'apachectl stop'. You will see warning and error
messages in error_log
[warn] child process 15317 still did not exit, sending a SIGTERM
[error] child process 15317 still did not exit, sending a SIGKILL
The problem goes away if I compile php without ZEND_SIGNALS.
I tried to analyze and debug zend_signal.c and found very wired behavior.
On first request zend_signal_activate() sets its own signal handler for
SIGHUP and stores the original handler in
SIGG(handlers)[SIGHUP-1].handler, but on second request the same
zend_signal_activate() overwrites the original signal handler by handler
from parent process.
zend_signal.c:284
memcpy(&SIGG(handlers), &global_orig_handlers,
sizeof(global_orig_handlers));
As result the original signal handler for SIGHUP is never called.
Even worse after restart and two request
SIGG(handlers)[SIGHUP-1].handler becomes SIG_IGN and SIGHUP is ignored
at all.
I'm not going to fix it myself.
Thanks. Dmitry.
On 02/08/2012 08:58 PM, Yoram bar-haim wrote:
Hello all.
After intensive debugging of PHP restart issues (child processes don't go down
fast enough for apache, so SIGTERM and sometimes SIGKILL are sent), I found
out the following problem in PHP signal handling mechanism.
on startup (zend_signal_startup()), :
PHP copies the current sigactions for all signals into
global_orig_handlers.
on activate (zend_signal_activate()) :
global_orig_handlers are copied int zend_global_handlers.
zend_signal_handler_defer is registered as signal handler (also in
zend_global_handlers).
Please note that zend_signal_startup() happens *before* set_signals() in
apache startup.
his logic works fine, unless SIGHUP is called after zend_signal_activate() was
started but before zend_signal_register() finished to register handler.
on that situation, the default (SIG_IGN) will found in
zend_global_handlers.handlers[0].handler by zend_signal_handler and the signal
will be ignored.
as result, child shutdown will not occur on SIGHUP but only later on SIGTERM.
I'm still trying to find a fix for this problem, but it will be better if Dmitry
ans Stas will also take a look.
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