Why Is My Apache Error Log Reporting 'child pid XXXX exit signal Segmentation fault (11)'?

"[notice] child pid XXXX exit signal Segmentation fault (11)" in apache error log

Apache Error Log Reporting Segmentation Fault

Many Apache users encounter seemingly blank white pages while using the Apache/PHP/MySQL stack, which cannot be debugged through Cake. Inspecting the Apache error log often reveals lines indicating "child pid XXXX exit signal Segmentation fault (11)." This error signifies a segmentation fault, where a memory location is accessed illegally.

Causes of Segmentation Fault

Segmentation faults can arise due to various reasons, including:

• Invalid memory access: Attempting to access a memory location outside the allocated block.
• Memory corruption: Accidentally writing or reading data in memory locations that are not intended.
• Illegal instructions: Executing instructions that the processor does not recognize.

Troubleshooting Segmentation Faults

To troubleshoot segmentation faults, follow these steps:

1. Attach GDB to a Child Process: Attach the GNU Debugger (GDB) to one of the HTTP child processes to retrieve a backtrace upon a crash.
2. Get Backtrace: Use the "backtrace" command to obtain a list of function calls leading to the crash. Include the backtrace in any bug report for further analysis.
3. Single Child Process Configuration: If the crash is difficult to reproduce, consider configuring Apache to use only one child process for handling requests by setting "StartServers," "MinSpareServers," and "MaxSpareServers" to 1.

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