We have a client who experienced this problem this morning. There’s no error or message because the PHP processes just spin before timing out.
The problem is in the database, which seems to be in a death spiral executing the following query over and over and over:
OPTIMIZE TABLE wp_blc_links, wp_blc_instances, wp_blc_synch
Especially on InnoDB, OPTIMIZE TABLE is an extremely expensive operation. Further, it’s blocking other normal queries on the wp_blc_instances table in Waiting for table level lock.
Unfortunately the only fix appears to be to completely remove the plugin folder, as we can’t even get wp plugin deactivate to work. Incidentally, here’s a partial strace of wp plugin list with timestamps so you can see where it’s hanging:
1590503980.171024 sendto(3, " \0\0\0\3SHOW INDEX FROMwp_blc_synch`;”, 36, MSG_DONTWAIT, NULL, 0) = 36
1590503980.171320 poll([{fd=3, events=POLLIN|POLLERR|POLLHUP}], 1, 1471228928) = 1 ([{fd=3, revents=POLLIN}])
1590503980.172042 recvfrom(3, “\1\0\0\1\rK\0\0\2\3def\22information_schema\nSTATISTICS\nSTATISTICS\5Table\nTABLE_NAME\f\340\0\0\1\0\0\375\1\0\0\0\0P\0\0\3\3def\22information_schema\nSTATISTICS\nSTATISTICS\nNon_unique\nNON_UNIQUE\f?\0\1\0\0\0\10\1\0\0\0\0N\0\0\4\3def\22information_schema\nSTATISTICS\nSTATISTICS\10Key_name\nINDEX_NAME\f\340\0\0\1\0\0\375\1\0\0\0\0T\0\0\5\3def\22information_schema\nSTATISTICS\nSTATISTICS\fSeq_in_index\fSEQ_IN_INDEX\f?\0\2\0\0\0\10\1\0\0\0\0R\0\0\6\3def\22information_schema\nSTATISTICS\nSTATISTICS\vColumn_name\vCOLUMN_NAME\f\340\0\0\1\0\0\375\1\0\0\0\0N\0\0\7\3def\22information_schema\nSTATISTICS\nSTATISTICS\tCollation\tCOLLATION\f\340\0\4\0\0\0\375\0\0\0\0\0R\0\0\10\3def\22information_schema\nSTATISTICS\nSTATISTICS\vCardinality\vCARDINALITY\f?\0\25\0\0\0\10\0\0\0\0\0L\0\0\t\3def\22information_schema\nSTATISTICS\nSTATISTICS\10Sub_part\10SUB_PART\f?\0\3\0\0\0\10\0\0\0\0\0H\0\0\n\3def\22information_schema\nSTATISTICS\nSTATISTICS\6Packed\6PACKED\f\340\0(\0\0\0\375\0\0\0\0\0H\0\0\v\3def\22information_schema\nSTATISTICS\nSTATISTICS\4Null\10NULLABLE\f\340\0\f\0\0\0\375\1\0\0\0\0P\0\0\f\3def\22information_schema\nSTATISTICS\nSTATISTICS\nIndex_type\nINDEX_TYPE\f\340\0@\0\0\0\375\1\0\0\0\0J\0\0\r\3def\22information_schema\nSTATISTICS\nSTATISTICS\7Comment\7COMMENT\f\340\0@\0\0\0\375\0\0\0\0\0V\0\0\16\3def\22information_schema\nSTATISTICS”…, 33666, MSG_DONTWAIT, NULL, NULL) = 1265
1590503980.172482 gettimeofday({tv_sec=1590503980, tv_usec=172531}, NULL) = 0
1590503980.172791 gettimeofday({tv_sec=1590503980, tv_usec=172838}, NULL) = 0
1590503980.173086 sendto(3, “R\0\0\0\3ALTER TABLE wp_blc_instances MODIFY COLUMN link_text text NOT NULL DEFAULT ””, 86, MSG_DONTWAIT, NULL, 0) = 86
1590503980.173497 poll([{fd=3, events=POLLIN|POLLERR|POLLHUP}], 1, 1471228928) = ? ERESTART_RESTARTBLOCK (Interrupted by signal)
1590504245.813742 — SIGINT {si_signo=SIGINT, si_code=SI_KERNEL} —
1590504246.116273 +++ killed by SIGINT +++`
Hopefully this helps!
