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From Sorin Manolache <sor...@gmail.com>
Subject Re: apr_shm_create succeeds then fails on Mac OS X
Date Sun, 27 Dec 2015 13:47:11 GMT
On 2015-12-25 19:36, Tapple Gao wrote:
> Hi. I’m trying to get mod_tile working on the builtin apache in Mac OS X El Capitan.
I am running into a problem with apr_shm_create failing to allocate memory during ap_hook_post_config:
> [Fri Dec 25 12:09:17.898197 2015] [tile:error] [pid 22431] Successfully create shared
memory segment size 888 on file /tmp/httpd_shm.22431
> [Fri Dec 25 12:09:17.898285 2015] [tile:error] [pid 22431] (12)Cannot allocate memory:
Failed to create shared memory segment size 2401448 on file /tmp/httpd_shm_delay.22431
>
> Is there something I need to configure to get this shared memory working, or increase
the limit? This module is most often run on Ubuntu linux, where it’s been running for years
to power openstreetmap.org
>
>
>      /*
>       * Create a unique filename using our pid. This information is
>       * stashed in the global variable so the children inherit it.
>       * TODO get the location from the environment $TMPDIR or somesuch.
>       */
>      shmfilename = apr_psprintf(pconf, "/tmp/httpd_shm.%ld", (long int)getpid());
>      shmfilename_delaypool = apr_psprintf(pconf, "/tmp/httpd_shm_delay.%ld", (long int)getpid());


I think that the location of the shmfile must be on a filesystem of a 
special type, namely tmpfs, which maps in memory and not on disk. 
Execute "mount" and check if you have such filesystems mounted. For 
example on my Linux machine:

$ mount
/dev/sda6 on / type ext4 (rw,relatime,errors=remount-ro,data=ordered)
tmpfs on /run/shm type tmpfs (rw,nosuid,nodev,noexec,relatime,size=398160k)
/dev/sda9 on /tmp type ext4 (rw,relatime,data=ordered)

As you see, / and /tmp are of disk partitions while /run/shm has a 
filesystem of type tmpfs.

I suggest to change the code and use a different location from /tmp/... 
On Linux the shared memory is often created in /run/shm/*. I have no 
experience with Mac OS X.

The cleanest way would be to implement what's written in the commentary 
of the code above, namely the possibility to specify the path by an 
evrionment variable or from a configuration directive.

Sorin


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