Using SystemTap with PHP DTrace Static Probes
On some Linux distributions, the SystemTap tracing utility can be used to trace PHP's static DTrace probes. This is available with PHP 5.4.20 and PHP 5.5.
Installing PHP with SystemTap
Install the SystemTap SDT development package:
# yum install systemtap-sdt-devel
Install PHP with the DTrace probes enabled:
# ./configure --enable-dtrace ... # make
Listing Static Probes with SystemTap
The static probes in PHP can be listed using stap:
# stap -l 'process.provider("php").mark("*")' -c 'sapi/cli/php -i'
This outputs:
process("sapi/cli/php").provider("php").mark("compile__file__entry")
process("sapi/cli/php").provider("php").mark("compile__file__return")
process("sapi/cli/php").provider("php").mark("error")
process("sapi/cli/php").provider("php").mark("exception__caught")
process("sapi/cli/php").provider("php").mark("exception__thrown")
process("sapi/cli/php").provider("php").mark("execute__entry")
process("sapi/cli/php").provider("php").mark("execute__return")
process("sapi/cli/php").provider("php").mark("function__entry")
process("sapi/cli/php").provider("php").mark("function__return")
process("sapi/cli/php").provider("php").mark("request__shutdown")
process("sapi/cli/php").provider("php").mark("request__startup")
SystemTap with PHP Example
Example #1 all_probes.stp for tracing all PHP Static Probes with SystemTap
probe process("sapi/cli/php").provider("php").mark("compile__file__entry") {
printf("Probe compile__file__entry\n");
printf(" compile_file %s\n", user_string($arg1));
printf(" compile_file_translated %s\n", user_string($arg2));
}
probe process("sapi/cli/php").provider("php").mark("compile__file__return") {
printf("Probe compile__file__return\n");
printf(" compile_file %s\n", user_string($arg1));
printf(" compile_file_translated %s\n", user_string($arg2));
}
probe process("sapi/cli/php").provider("php").mark("error") {
printf("Probe error\n");
printf(" errormsg %s\n", user_string($arg1));
printf(" request_file %s\n", user_string($arg2));
printf(" lineno %d\n", $arg3);
}
probe process("sapi/cli/php").provider("php").mark("exception__caught") {
printf("Probe exception__caught\n");
printf(" classname %s\n", user_string($arg1));
}
probe process("sapi/cli/php").provider("php").mark("exception__thrown") {
printf("Probe exception__thrown\n");
printf(" classname %s\n", user_string($arg1));
}
probe process("sapi/cli/php").provider("php").mark("execute__entry") {
printf("Probe execute__entry\n");
printf(" request_file %s\n", user_string($arg1));
printf(" lineno %d\n", $arg2);
}
probe process("sapi/cli/php").provider("php").mark("execute__return") {
printf("Probe execute__return\n");
printf(" request_file %s\n", user_string($arg1));
printf(" lineno %d\n", $arg2);
}
probe process("sapi/cli/php").provider("php").mark("function__entry") {
printf("Probe function__entry\n");
printf(" function_name %s\n", user_string($arg1));
printf(" request_file %s\n", user_string($arg2));
printf(" lineno %d\n", $arg3);
printf(" classname %s\n", user_string($arg4));
printf(" scope %s\n", user_string($arg5));
}
probe process("sapi/cli/php").provider("php").mark("function__return") {
printf("Probe function__return: %s\n", user_string($arg1));
printf(" function_name %s\n", user_string($arg1));
printf(" request_file %s\n", user_string($arg2));
printf(" lineno %d\n", $arg3);
printf(" classname %s\n", user_string($arg4));
printf(" scope %s\n", user_string($arg5));
}
probe process("sapi/cli/php").provider("php").mark("request__shutdown") {
printf("Probe request__shutdown\n");
printf(" file %s\n", user_string($arg1));
printf(" request_uri %s\n", user_string($arg2));
printf(" request_method %s\n", user_string($arg3));
}
probe process("sapi/cli/php").provider("php").mark("request__startup") {
printf("Probe request__startup\n");
printf(" file %s\n", user_string($arg1));
printf(" request_uri %s\n", user_string($arg2));
printf(" request_method %s\n", user_string($arg3));
}
The above script will trace all core PHP static probe points throughout the duration of a running PHP script:
# stap -c 'sapi/cli/php test.php' all_probes.stp
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