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From Jeff Trawick <traw...@gmail.com>
Subject Re: [users@httpd] Interrupted system call: Failed to acquire SSL session cache lock
Date Tue, 15 Jul 2014 21:06:11 GMT
On Tue, Jul 15, 2014 at 4:55 PM, Tomlinson, Stuart <st024y@intl.att.com>
wrote:

> Hello,
>
> We have experienced this warning/error a few times:
> [Thu Jul 03 20:17:15 2014] [warn] (4)Interrupted system call: Failed to
> acquire SSL session cache lock
>
> After this has occurred, the Apache ErrorLog is flooded with these errors:
> [Thu Jul 03 20:17:57 2014] [error] shmcb_subcache_retrieve internal error
>

It looks like there is a bug in the APR library.  It doesn't handle EINTR
("Interrupted system call") in the POSIX semaphore implementation.


[Thu Jul 03 20:17:58 2014] [error] shmcb_subcache_retrieve internal error
> [Thu Jul 03 20:17:58 2014] [error] shmcb_subcache_retrieve internal error
> [Thu Jul 03 20:17:59 2014] [error] shmcb_subcache_retrieve internal error
>
> Other symptoms as a result of this condition are significantly increased
> CPU utilization (at least doubled), and increase in time to establish
> connections when trying to use SSL session caching (tested with "openssl
> s_client -state -reconnect -connect server:port"). Apache restart is
> required to restore normal behavior.
>
> I have been unable to find any details of what the cause of this condition
> is, or how to prevent it having such undesirable consequences. Is this a
> known issue, or does anyone have any suggestions on how to prevent it
> happening again?
>
> OS: RHEL 5.9
> OpenSSL version: 1.0.0e
> Apache httpd version: 2.2.21
> Apache configure options used:
> ./configure --with-mpm=worker --with-included-apr \
>             --enable-static-support --enable-mods-shared=most \
>             --enable-proxy=shared --enable-proxy-connect=shared \
>             --enable-proxy-ftp=shared --enable-proxy-http=shared \
>             --enable-proxy-ajp=shared --enable-proxy-balancer=shared \
>             --enable-deflate --with-z=${PREFIX} \
>             --enable-ssl --with-ssl=${PREFIX} \
>             --prefix=${PREFIX}
>
> SSL related configuration options:
> SSLEngine on
> SSLSessionCache        "shmcb:/path/to/ssl_scache(512000)"
> SSLSessionCacheTimeout  300
> SSLMutex sem
>

Use "SSLMutex sysvsem" instead.



> SSLProtocol all -SSLv2
> SSLCipherSuite
> ALL:!ADH:!EXPORT56:RC4+RSA:+HIGH:+MEDIUM:-LOW:-SSLv2:-EXP:-eNULL:-NULL
>
>
> Regards,
>
>
> Stu Tomlinson.
>
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>


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Born in Roswell... married an alien...
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