Bug #69637 [Com]: stream_select() warns: recompile php with FD_SETSIZE>1024 but it already is

From: Date: Wed, 30 Jan 2019 11:34:28 +0000
Subject: Bug #69637 [Com]: stream_select() warns: recompile php with FD_SETSIZE>1024 but it already is
References: 1  Groups: php.bugs 
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Edit report at https://bugs.php.net/bug.php?id=69637&edit=1

 ID:                 69637
 Comment by:         stormdja at gmail dot com
 Reported by:        bousset1 at gmail dot com
 Summary:            stream_select() warns: recompile php with
                     FD_SETSIZE>1024 but it already is
 Status:             Verified
 Type:               Bug
 Package:            Sockets related
 Operating System:   linux (tested on ubuntu 14.04)
 PHP Version:        5.6.8
 Block user comment: N
 Private report:     N

 New Comment:

@[2016-11-08 10:45 UTC] - directly modifiying system headers may not be a good idea.
Here's a simple patch (tested on php 7.2.14):
--- main/php.h    2019-01-08 09:59:17.000000000 +0000
+++ main/php.h    2019-01-30 09:03:18.698899000 +0000
@@ -515,6 +515,11 @@
 
 #endif
 
+#undef __FD_SETSIZE
+#define __FD_SETSIZE 32768
+#undef FD_SETSIZE
+#define FD_SETSIZE 32768
+
 /*
  * Local variables:
  * tab-width: 4

-----------
Result:
# php-7.2.14-009/bin/php -r "print_r(get_defined_constants(true));"|grep FD_SETSIZE
            [PHP_FD_SETSIZE] => 32768


Previous Comments:
------------------------------------------------------------------------
[2017-04-24 19:05:58] erw at macrovita dot com dot br

If PHP process has more open file descriptors than FD_SETSIZE, it seems stream_select() will fail
even when trying to monitor just a couple file descriptors.

I get the error even when trying to stream_select() only 2 file descriptors, apparently because the
apache process has thousands of file descriptors open.

Environment: apache-2.4.23 event mpm, php-7.0.11, Gentoo Linux

// BTM11121, BTM10159

------------------------------------------------------------------------
[2016-11-08 10:45:07] kexianbin at diyism dot com

1.vi /usr/include/x86_64-linux-gnu/bits/typesizes.h:
#define __FD_SETSIZE  65536

2.compile:
./configure --with-curl --enable-fd-setsize=65536 CFLAGS='-D_FORTIFY_SOURCE=0'
make && sudo make install

3.vi /etc/security/limits.conf:
* soft nofile 65535
* hard nofile 65535

------------------------------------------------------------------------
[2016-07-03 12:30:29] cmb@php.net

Related To: Bug #43269

------------------------------------------------------------------------
[2016-07-02 15:20:57] cmb@php.net

Related To: Bug #72030

------------------------------------------------------------------------
[2016-05-31 21:05:34] deriamis at gmail dot com

The reason this appears to be happening is that sys/select.h on Linux is overriding FD_SETSIZE by
setting it to the value of __FD_SETSIZE, which is set statically to 1024, without checking that
it's already defined. The --enable-fd-setsize is not cross-platform and, people who need this
either have to patch PHP source in several places (bad) or system include files (worse). I think a
good way to do this is to set a dummy value and then in source set both FD_SETSIZE and __FD_SETSIZE
to the dummy value immediately before the sys/select.h include.

------------------------------------------------------------------------


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