From: sopl dot wang at gmail dot com
Operating system: ALL
PHP version: master-Git-2012-07-25 (Git)
Package: cURL related
Bug Type: Bug
Bug description:When enable âwith-curlwrappers option, stream_get_contents()
may cpu 100%
Description:
------------
When enable `âwith-curlwrappers` option, with http(s)/ftp(s)/other
curl-wrapped
stream protocols, file_get_contents(), stream_get_contents() and alike
functions
may lead consume 100% cpu cycle on waiting for receive.
When `strace` problem php process, following will be develop:
<pre>
select(7, [6], [6], [], {15, 0}) = 1 (out [6], left {15, 0})
poll([{fd=6, events=POLLIN}], 1, 0) = 0 (Timeout)
select(7, [6], [6], [], {15, 0}) = 1 (out [6], left {15, 0})
poll([{fd=6, events=POLLIN}], 1, 0) = 0 (Timeout)
select(7, [6], [6], [], {15, 0}) = 1 (out [6], left {15, 0})
poll([{fd=6, events=POLLIN}], 1, 0) = 0 (Timeout)
select(7, [6], [6], [], {15, 0}) = 1 (out [6], left {15, 0})
poll([{fd=6, events=POLLIN}], 1, 0) = 0 (Timeout)
select(7, [6], [6], [], {15, 0}) = 1 (out [6], left {15, 0})
poll([{fd=6, events=POLLIN}], 1, 0) = 0 (Timeout)
select(7, [6], [6], [], {15, 0}) = 1 (out [6], left {15, 0})
poll([{fd=6, events=POLLIN}], 1, 0) = 0 (Timeout)
select(7, [6], [6], [], {15, 0}) = 1 (out [6], left {15, 0})
poll([{fd=6, events=POLLIN}], 1, 0) = 0 (Timeout)
select(7, [6], [6], [], {15, 0}) = 1 (out [6], left {15, 0})
poll([{fd=6, events=POLLIN}], 1, 0) = 0 (Timeout)
select(7, [6], [6], [], {15, 0}) = 1 (out [6], left {15, 0})
poll([{fd=6, events=POLLIN}], 1, 0) = 0 (Timeout)
select(7, [6], [6], [], {15, 0}) = 1 (out [6], left {15, 0})
poll([{fd=6, events=POLLIN}], 1, 0) = 0 (Timeout)
</pre>
The reason we found is in 'ext/curl/streams.c', function
php_curl_stream_read(),
line 174:
<code>
select(curlstream->maxfd + 1, &curlstream->readfds,
&curlstream->writefds,
&curlstream->excfds, &tv)
</code>
When select(), `writefds` always can write and immediate return, no block
at
here and, upper module will detect that no data could read and re-invoke
this
function (`php_curl_stream_read()`), a nonblock loop, lead this consume
100% cpu
bug.
If the link very slow, this 100% cpu problem may take the system load very
high.
Test script:
---------------
Enable `âwith-curlwrappers` and test:
<code>
<?php
while (true)
file_get_contents('http://soplwang.com');
</code>
Expected result:
----------------
Expect the behavior like native php doesâ¦
When `strace`, native php generate:
<pre>
poll([{fd=3, events=POLLIN|POLLERR|POLLHUP}], 1, 60000) = 1 ([{fd=3,
revents=POLLIN}])
</pre>
Actual result:
--------------
When `strace`, generate:
<pre>
select(4, [3], [3], [], {15, 0}) = 1 (out [3], left {15, 0})
poll([{fd=3, events=POLLIN}], 1, 0) = 0 (Timeout)
select(4, [3], [3], [], {15, 0}) = 1 (out [3], left {15, 0})
poll([{fd=3, events=POLLIN}], 1, 0) = 0 (Timeout)
select(4, [3], [3], [], {15, 0}) = 1 (out [3], left {15, 0})
poll([{fd=3, events=POLLIN}], 1, 0) = 0 (Timeout)
select(4, [3], [3], [], {15, 0}) = 1 (out [3], left {15, 0})
poll([{fd=3, events=POLLIN}], 1, 0) = 0 (Timeout)
select(4, [3], [3], [], {15, 0}) = 1 (out [3], left {15, 0})
poll([{fd=3, events=POLLIN}], 1, 0) = 0 (Timeout)
...
</pre>
--
Edit bug report at https://bugs.php.net/bug.php?id=62658&edit=1
--
Try a snapshot (PHP 5.4):
https://bugs.php.net/fix.php?id=62658&r=trysnapshot54
Try a snapshot (PHP 5.3):
https://bugs.php.net/fix.php?id=62658&r=trysnapshot53
Try a snapshot (trunk):
https://bugs.php.net/fix.php?id=62658&r=trysnapshottrunk
Fixed in SVN:
https://bugs.php.net/fix.php?id=62658&r=fixed
Fixed in SVN and need be documented:
https://bugs.php.net/fix.php?id=62658&r=needdocs
Fixed in release:
https://bugs.php.net/fix.php?id=62658&r=alreadyfixed
Need backtrace:
https://bugs.php.net/fix.php?id=62658&r=needtrace
Need Reproduce Script:
https://bugs.php.net/fix.php?id=62658&r=needscript
Try newer version:
https://bugs.php.net/fix.php?id=62658&r=oldversion
Not developer issue:
https://bugs.php.net/fix.php?id=62658&r=support
Expected behavior:
https://bugs.php.net/fix.php?id=62658&r=notwrong
Not enough info:
https://bugs.php.net/fix.php?id=62658&r=notenoughinfo
Submitted twice:
https://bugs.php.net/fix.php?id=62658&r=submittedtwice
register_globals:
https://bugs.php.net/fix.php?id=62658&r=globals
PHP 4 support discontinued:
https://bugs.php.net/fix.php?id=62658&r=php4
Daylight Savings: https://bugs.php.net/fix.php?id=62658&r=dst
IIS Stability:
https://bugs.php.net/fix.php?id=62658&r=isapi
Install GNU Sed:
https://bugs.php.net/fix.php?id=62658&r=gnused
Floating point limitations:
https://bugs.php.net/fix.php?id=62658&r=float
No Zend Extensions:
https://bugs.php.net/fix.php?id=62658&r=nozend
MySQL Configuration Error:
https://bugs.php.net/fix.php?id=62658&r=mysqlcfg
