| Bug #112727 | MySQL may couldn't solve the error when flush thread caches to binary logs | ||
|---|---|---|---|
| Submitted: | 15 Oct 2023 4:17 | Modified: | 19 Oct 2023 11:10 |
| Reporter: | Yawei Sun | Email Updates: | |
| Status: | Not a Bug | Impact on me: | |
| Category: | MySQL Server: Replication | Severity: | S3 (Non-critical) |
| Version: | MySQL8.0.22, 8.0.23 | OS: | Any |
| Assigned to: | MySQL Verification Team | CPU Architecture: | Any |
[19 Oct 2023 11:10]
MySQL Verification Team
HI Mr. Sun, Thank you for your bug report. However, your analysis is wrong. Simply, if you analyse the entire function, you will notice that flush_error can be changed ONLY once regardless of the number of passes in the loop. Hence, this is not a bug.
Description: In loop of the function MYSQL_BIN_LOG::process_flush_stage_queue (src/binlog.cc), only when flush_error == 1 that the value of flush_error will be change, and the result is returned by functioun flush_thread_caches(), the function return error code on error, zero if no error. So there is a scene that in the beginning loops of the function MYSQL_BIN_LOG::process_flush_stage_queue, we successfully flush caches, so flush_error will be set to 0, however it did not flush successfully in the next loop, because flush_error == 0 at this time, so the error this time will not be recorded and nobody know there is exist an error when fulsh caches. The related function calling relationships are as follows: MYSQL_BIN_LOG::ordered_commit --> MYSQL_BIN_LOG::process_flush_stage_queue --> MYSQL_BIN_LOG::flush_thread_cache --> binlog_cache_mngr::flush The related code in MYSQL_BIN_LOG::process_flush_stage_queue are as follows: for (THD *head = first_seen; head; head = head->next_to_commit) { Thd_backup_and_restore switch_thd(current_thd, head); std::pair<int, my_off_t> result = flush_thread_caches(head); total_bytes += result.second; if (flush_error == 1) flush_error = result.first; #ifndef NDEBUG no_flushes++; #endif } How to repeat: It's a code bug now i haven't create a scene to repeat