Comment 1 for bug 1428541

I apologize, it seems I misunderstood the status of related former reports:
lp:1126316 and lp:1271177
as if this was fixed already and blocking should no longer occur.

However it seems that this behavior for SHOW STATUS is intended when causal reads are set, and one should disable it per session to make SHOW STATUS to work under Flow Control condition.
I don't understand why blocking of reading the status variables is needed for causal reads, but if this is indeed necessary and intended, let's close this one with duplicate status.

Anyways, the workaround and the only method for any monitoring tools is to do:

percona30 mysql> set session wsrep_sync_wait=0;
Query OK, 0 rows affected (0.00 sec)

percona30 mysql> show status like 'ws%recv_q%';
+----------------------------+-----------+
| Variable_name | Value |
+----------------------------+-----------+
| wsrep_local_recv_queue | 29 |
| wsrep_local_recv_queue_max | 30 |
| wsrep_local_recv_queue_min | 0 |
| wsrep_local_recv_queue_avg | 12.584416 |
+----------------------------+-----------+
4 rows in set (0.00 sec)