Phy. Log Overflow,CKPT Blocked

Hi, We run Online 7.14UD1 on MP-RAS. The engine was hanging with the CKPT blocked message.The message log indicated a physical log overflow. The onstat -u output was explanatory 29abe784 Y--P--- 1287 29abf420 --RPX-- 1370 29ac118c C-BP--- 1281 29ac19f4 Y--P--- 1262 29ac332c ---P--- 1293 29ac3760 Y--P--- 1154 29ac5900 C--P--- 1377 29ac5d34 ---P--- 1369 So I inferred that the thread in Critical section caused the Phy. Log overflow. (Thanks to Art.S.Kagel's classic explanation of the Phy.Log overflow recently). But why does the CKPT block, causing Online to hang while a Phy.Log overflow occurs ? Has anyone seen this "mt.c", invariably this shows up whenever online crashes. TIA Sathish Sadagopan Contents of message log ------------------------------------ 11:04:43 Assert Failed: Physical log file overflow 11:04:43 Who:Session(1370, sadagop@serv, 26115, 699268812) Thread(35335, sqlexec, 29abf420, 7) 11:04:43 Results: OnLine must abort 11:04:43 Action: Reinitialize shared memory 11:04:43 See Also: /infxshm/af.8a07d29b, shmem.8a07d29b.0, /usr/informix/core 11:14:20 mt.c, line 8994, thread 7, proc id 567, Unexpected virtualprocessor t ermination, pid = 573, exit = 0xb . Contents of af.* file ---------------------------- 11:04:43 Physical log file overflow physlog_t ........ 11:04:43 Assert Failed: Physical log file overflow 11:04:43 Who:Session(1370, sadagop@serv, 26115, 699268812) Thread(35335, sqlexec, 29abf420, 7) 11:04:43 Results: OnLine must abort 11:04:43 Action: Reinitialize shared memory 11:04:43 See Also: /infxshm/af.8a07d29b, shmem.8a07d29b.0, /usr/informix/core 11:04:43 Stack for thread: 35335 sqlexec base: 0x2a260358 len: 36864 pc: 0x082e46fd tos: 0x2a268adc

Sadagopan, Sathish, CFCTR wrote: > Hi, > We run Online 7.14UD1 on MP-RAS. > The engine was hanging with the CKPT blocked message.The message log > indicated a physical log overflow. > The onstat -u output was explanatory > 29abe784 Y--P--- 1287 > 29abf420 --RPX-- 1370 > 29ac118c C-BP--- 1281 > 29ac19f4 Y--P--- 1262 > 29ac332c ---P--- 1293 > 29ac3760 Y--P--- 1154 > 29ac5900 C--P--- 1377 > 29ac5d34 ---P--- 1369 > So I inferred that the thread in Critical section caused the Phy. Log > overflow. > (Thanks to Art.S.Kagel's classic explanation of the Phy.Log overflow > recently). You are welcome. > But why does the CKPT block, causing Online to hang while a Phy.Log overflow > occurs ? It is not blocked for the Phys Log overflow but for the critical query in critical section. The checkpoint starts by issuing a block that stops new transactions beginning until the checkpoint completes, then it waits for all threads in critical section to free themselves and block waiting for the checkpoint thread. Only when all threads requiring critical section latches are blocked can the checkpoint continue. Here you are waiting for a thread in a, probably HUGE, rollback which is a critical section itself, before the checkpoint can start. While this was going on additional records were written to the physical log and it overflowed. > Has anyone seen this "mt.c", invariably this shows up whenever online > crashes. [SNIP] I think that mt.c is the source for the mainline of the monitor thread in the misc VP that watches to make sure the other VPs stay online. Art S. Kagel