Core dumps and gdb backtrace for php-fpm and apache

Core dumps and gdb backtrace for apache

#PHP Apache CORE DUMP - GDB backtrace

Open httpd.conf:
    vi httpd.conf

Add following line main config section:
    ```CoreDumpDirectory /tmp/apache2-gdb-dump```

Unlimited core dump size, In terminal add below
    ```ulimit -c unlimited```


Create a directory /tmp/apache2-gdb-dump:
    ```mkdir -p /tmp/apache2-gdb-dump```

Set permission:
    ```chown httpd:appserver /tmp/apache2-gdb-dump
    chmod 0777 /tmp/apache2-gdb-dump```

Now you should see core dumps in /tmp/apache2-gdb-dump directory:
    ```ls /tmp/apache2-gdb-dump```

Install GDB
    ```yum install gdb``` or ```apt-get install gdb``` or ```.....check online```

Reading the core dumps

    ```gdb $program-path $coredump-path or gdb -c <core_file> `which <program-path>`
    Example:
        gdb /usr/sbin/php-fpm /tmp/apache2-gdb-dump```

 with in GDB
 ```   
    * set disassembly-flavor intel
    * set logging on
    * bt full
    * info reg
    * disassemble
    * info shared
    * Info threads
```

Core dumps and gdb backtrace for php-fpm

#PHP-FPM CORE DUMP - GDB backtrace

Check if core dump is enabled or not
```
    ls /tmp/coredump*
```

If not, Enable core dumps
1. Create core dump file and point to the kernel core_pattern
```
    echo '/tmp/coredump-%e.%p' > /proc/sys/kernel/core_pattern
```
2. Open your php-fpm pool configuration and add
```
    rlimit_core = unlimited
```

Unlimited core dump size, In terminal add below
```
    ulimit -c unlimited
```

Install GDB
       ```yum install gdb``` or ```apt-get install gdb``` or ```.....check online```

Reading the core dumps

        ```gdb $program-path $coredump-path or gdb -c <core_file> `which <program-path>`
        Example:
            gdb /usr/sbin/php-fpm /tmp/coredump-php-fpm.2393```

 with in GDB
 ```
    * set disassembly-flavor intel
    * set logging on
    * bt full
    * info reg
    * disassemble
    * info shared
    * Info threads
```

disassembly to disassemble