I ran into one of the hardest things to figure out the dreaded “Segmentation fault” and “Illegal instruction” while running php-cli in a QP2TERM session (a PASE/AIX/”IBMs unix” shell). The exact errors were:
php-cli: 12345 Illegal instruction (coredump) –when ran non-interactive
php-cli: 12345 Segmentation fault(coredump) –when ran interactive
Note: php-cli is the shell script that calls the PHP interpreter on line 9 from the command line and 12345 is the AIX process id that had the issue. Segmentation fault means you are addressing memory outside of your data segment which has a predefined size (256MB). coredump should be a data dump in the system log
In /usr/local/zendsvr/etc/php.ini I tried to increase the
memory_limit = 512M ; Maximum amount of memory a script may consume (512M).
I tried to set the value in my script with
I even tried to set it on the command line with the -d option
/usr/local/zendsvr/bin/php-cli -d memory_limit=512M myscript.php
I figured out the amount of memory my script was using by reducing the number of records it was processing and running the follow echo command to get the peak memory usage:
echo “Memory Peak Usage: “.(memory_get_peak_usage()/1024/1024).” MB”;
The actual memory bottle neck was happening further up the chain at the AIX process/job level. The default memory limit of AIX process is 256MB with additional Data Segments of 256MB (Hex 0x10000000 2^8) with a max size of 8 additional data segments
Set the LDR_CNTRL environment variable in the parent process (PHP-CLI) to multiple data segments (in the example below 8 additional data segments of 256MB for 2.25GB of memory [this is the max…]) and then run your php script and then unset the memory limit so you don’t affect other processes. Modify the shell script /usr/local/zendsvr/bin/php-cli and wrap the call to the php interpreter ($ZCE_PREFIX/bin/php “$@”) with the export and unsetting of LDR_CNTRL as shown below
putenv should probably not work because the parent process has to set LDR_CNTRL not the PHP script
Use echo getenv(“LDR_CNTRL”); to see what its set to in your PHP script.
If you are using the FASTCGI w/ apache you can modify the config file (/www/zendsvr/conf/fastcgi.conf) and add to the end of the line starting with Server type=”application/x-httpd-php” …
If you are hitting this limit you should probably look at the program you created because there may be something that is inefficiently using memory and that should be fixed instead of changing the memory limit.
What is this DSA
“The @DSA which can be appended to this value allows the boundary been private data and shared memory to be changed, allowing more segments to be used and the heap to start in segment 3. It also allows shared objects to be moved into segment 2 to give more contiguous space (See Figure 4).” – http://ibmsystemsmag.com/CMSTemplates/IBMSystemsMag/Print.aspx?path=/aix/administrator/systemsmanagement/Avoiding-Those–Segmentation-Fault–Failure-Messag
More info here: https://www.ibm.com/support/knowledgecenter/en/ssw_aix_61/com.ibm.aix.genprogc/lrg_prg_support.htm
These issues might also go away when we go from 32 bit to 64 bit.