| Bug #104405 | show processlist return -1 in TIME field | ||
|---|---|---|---|
| Submitted: | 24 Jul 2021 5:44 | Modified: | 26 Jul 2021 5:50 |
| Reporter: | yuxiang jiang (OCA) | Email Updates: | |
| Status: | Verified | Impact on me: | |
| Category: | MySQL Server: Information schema | Severity: | S3 (Non-critical) |
| Version: | 5.7.18, 8.0 | OS: | Any |
| Assigned to: | CPU Architecture: | Any | |
| Tags: | Contribution | ||
[24 Jul 2021 16:43]
yuxiang jiang
bugfix for this defect (*) I confirm the code being submitted is offered under the terms of the OCA, and that I am authorized to contribute it.
Contribution: 0001-bugfix-issue-422-show-processlist-return-invalid-val.patch (application/octet-stream, text), 1.58 KiB.
[26 Jul 2021 5:50]
MySQL Verification Team
Hello yuxiang jiang, Thank you for the report and contribution. regards, Umesh
Description: SQL command “show processlist;” return -1 in TIME field occasionally， while TIME field should not be negative. This will happen more frequently when instance has several connections. The reason is that start time and end time are measured by different method. In very short time, (longlong) (now - thd_info->start_time) maybe negative. if (thd_info->start_time) protocol->store_long ((longlong) (now - thd_info->start_time)); else protocol->store_null(); How to repeat: We can use code below void test_my_time_and_micro_time_now() { ulonglong start_utime; struct timeval start_time; time_t now; int counter = 0, trig_counter = 0; while (true) { start_utime= my_micro_time(); my_micro_time_to_timeval(start_utime, &start_time); usleep(10); now= my_time(0); longlong diff= now - start_time.tv_sec; if (diff < 0) { trig_counter++; } counter++; if (trig_counter > 100) break; } if (trig_counter) { sql_print_error("my_time function and my_micro_time_to_timeval function " "has fraction diff trigger %d in %d", trig_counter, counter); } } Suggested fix: Return 0 if (longlong) (now - thd_info->start_time) is negative.