PS-8908: Mysqld crash when user forgets to set debug timeout #5117
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https://jira.percona.com/browse/PS-8908 Problem: If 'debug_sync_timeout' parameter is not specified in my.cnf or as a command line argument, the usage of debug sync factility leads to the assertion. Cause: The default value of 'debug_sync_timeout' is 0, which means the debug sync factility is disabled. In such a case 'debug_sync_control' member of the THD is not initialized during THD initialization (debug_sync_init_thread()). The callstack debug_sync_set_action => debug_sync_eval_action => debug_sync_get_action uses 'debug_sync_control' member unconditionally causing the assertion. Solution: There was a missing check for 'debug_sync_timeout' in the above-mentioned callstack. Similar checks are present in debug_sync_update() or debug_sync_init() functions. Added missing check.
satya-bodapati
requested changes
Jan 2, 2024
| @@ -1975,6 +1975,11 @@ bool debug_sync_set_action(THD *thd, const char *action_str, size_t len) { | |||
| assert(thd); | |||
| assert(action_str); | |||
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| // A zero value keeps the facility disabled. | |||
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I guess MTR framework always has debug sync enabled? Is it possible to use different cnf or start mysqld without debug sync enabled and execute testcase provided in the bug report?
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Yes, probably MTR framework always sets debug_sync_timeout, so the problem is not visible. The problem is visible if you start the server standalone without specifying it and execute debug sync queries manually like it is in the bug report.
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https://jira.percona.com/browse/PS-8908
Problem:
If 'debug_sync_timeout' parameter is not specified in my.cnf or as a command line argument, the usage of debug sync factility leads to the assertion.
Cause:
The default value of 'debug_sync_timeout' is 0, which means the debug sync factility is disabled. In such a case 'debug_sync_control' member of the THD is not initialized during THD initialization (debug_sync_init_thread()).
The callstack debug_sync_set_action => debug_sync_eval_action => debug_sync_get_action uses 'debug_sync_control' member unconditionally causing the assertion.
Solution:
There was a missing check for 'debug_sync_timeout' in the above-mentioned callstack. Similar checks are present in debug_sync_update() or debug_sync_init() functions. Added missing check.