RE: dynamically allocated new shared memory segment - What is thi

Gary, You may be encountering the following software defect: 100419 USING NVL FUNCTION ON 7.30 CAUSES 2 OR 3 SHARED MEMORY QUERY WITHOUT NVL FUNCTION DOES NOT. We encountered this "bug" in IDS 7.30.UC3. It was subsequently fixed. Check your release notes ($INFORMIXDIR/release/en_us/0333/SERVERS_7.3) to determine if it has been fixed in your version. If not, you should consider an upgrade or rewrite your queries. The CASE statement can also be used to convert a null value to a non-null value. Rick Bernstein -----Original Message----- From: Gary Quiring To: informix-list@iiug.org Sent: 4/5/00 6:38 PM Subject: dynamically allocated new shared memory segment - What is this? We had a pause in our Informix 7.3 system today around 5:00pm. The system just 'froze' for almost a minute. Is there something that needs to be tuned? This is the log during that period: Thanks Gary Quiring 16:44:50 Logical Log 23611 Complete. 16:48:13 Logical Log 23612 Complete. 16:49:25 Checkpoint Completed: duration was 12 seconds. 16:52:56 Logical Log 23613 Complete. 16:54:41 Checkpoint Completed: duration was 13 seconds. 16:55:05 dynamically allocated new shared memory segment (size 33554432) 16:55:44 dynamically allocated new shared memory segment (size 33554432) 16:58:20 Logical Log 23614 Complete. 17:00:17 Checkpoint Completed: duration was 32 seconds. 17:04:02 Logical Log 23615 Complete. 17:05:33 Checkpoint Completed: duration was 12 seconds. 17:10:42 Checkpoint Completed: duration was 7 seconds. 17:13:00 Logical Log 23616 Complete. onconfig file: ROOTNAME rootdbs # Root dbspace name ROOTPATH /dev/lrootdbs # Path for device containing rootdbspace ROOTOFFSET 0 # Offset of root dbspace into device (Kbytes) ROOTSIZE 200000 # Size of root dbspace (Kbytes) # Disk Mirroring Configuration Parameters MIRROR 0 # Mirroring flag (Yes = 1, No = 0) MIRRORPATH # Path for device containing mirroredroot MIRROROFFSET 0 # Offset into mirrored device (Kbytes) # Physical Log Configuration PHYSDBS plogdbs PHYSFILE 100000 # Logical Log Configuration LOGFILES 100 # Number of logical log files LOGSIZE 2500 # Logical log size (Kbytes) # Diagnostics MSGPATH /u/ifmx/online.log # System message log file path CONSOLE /dev/console # System console message path ALARMPROGRAM # /u/ifmx/etc/log_full.sh # Alarm program pathSYSALARMPROGRAM /u/ifmx/etc/evidence.sh # System Alarm program path TBLSPACE_STATS 1 # Optical STAGEBLOB # Informix Dynamic Server/Optical staging area # System Configuration SERVERNUM 0 # Unique id corresponding to a DynamicServer in stance DBSERVERNAME emco1_shm # Name of default database server DBSERVERALIASES emco1_net # List of alternate dbservernames NETTYPE ipcshm,2,200,CPU # Configure poll thread(s) for sharedmem NETTYPE tlitcp,2,130,NET # Configure poll thread(s) fornetwork DEADLOCK_TIMEOUT 60 # Max time to wait of lock indistributed env. RESIDENT 1 # Forced residency flag (Yes = 1, No = 0) MULTIPROCESSOR 1 # 0 for single-processor, 1 formulti-processor NUMCPUVPS 3 # Number of user (cpu) vps SINGLE_CPU_VP 0 # If non-zero, limit number of cpu vpsto one NOAGE 1 # Process aging AFF_SPROC 0 # Affinity start processor AFF_NPROCS 0 # Affinity number of processors # Shared Memory Parameters LOCKS 1000000 # Maximum number of locks BUFFERS 300000 # Maximum number of shared buffers NUMAIOVPS # Number of IO vps PHYSBUFF 32 # Physical log buffer size (Kbytes) LOGBUFF 32 # Logical log buffer size (Kbytes)LOGSMAX 200 # Maximum number of logical log files CLEANERS 20 # Number of buffer cleaner processes SHMBASE 0x82000000 # Shared memory base address SHMVIRTSIZE 131072 # initial virtual shared memorysegment size SHMADD 32768 # Size of new shared memory segments (Kbytes) SHMTOTAL 0 # Total shared memory (Kbytes). 0=>unlimited CKPTINTVL 300 # Check point interval (in sec) LRUS 20 # Number of LRU queues LRU_MAX_DIRTY 3 # LRU percent dirty begin cleaninglimit LRU_MIN_DIRTY 1 # LRU percent dirty end cleaning limit LTXHWM 40 # Long transaction high water markpercentage LTXEHWM 50 # Long transaction high water mark (exclusive) TXTIMEOUT 0x12c # Transaction timeout (in sec) STACKSIZE 32 # Stack size (Kbytes) # Recovery Variables # OFF_RECVRY_THREADS: # Number of parallel worker threads during fast recovery or an offline restore. # ON_RECVRY_THREADS: # Number of parallel worker threads during an online restore. OFF_RECVRY_THREADS 10 # Default number of offline workerthreads ON_RECVRY_THREADS 1 # Default number of online workerthreads # Data Replication Variables # DRAUTO: 0 manual, 1 retain type, 2 reverse type DRAUTO 0 # DR automatic switchover DRINTERVAL 30 # DR max time between DR buffer flushes (in sec) DRTIMEOUT 30 # DR network timeout (in sec) DRLOSTFOUND /u/ifmx/etc/dr.lostfound # DR lost+found file path # CDR Variables CDR_LOGBUFFERS 2048 # size of log reading buffer pool (Kbytes) CDR_EVALTHREADS 1,2 # evaluator threads (per-cpu-vp,additional) CDR_DSLOCKWAIT 5 # DS lockwait timeout (seconds) CDR_QUEUEMEM 4096 # Maximum amount of memory for any CDR queue (Kb ytes) # Backup/Restore variables BAR_ACT_LOG /tmp/bar_act.log BAR_MAX_BACKUP 0 BAR_RETRY 1 BAR_NB_XPORT_COUNT 10 BAR_XFER_BUF_SIZE 31 # Informix Storage Manager variables ISM_DATA_POOL ISMData # If the data pool name is changed, be sure to # update $INFORMIXDIR/bin/onbar. Change to # ism_catalog -create_bootstrap -pool <new name> ISM_LOG_POOL ISMLogs # Read Ahead Variables RA_PAGES # Number of pages to attempt to readahead RA_THRESHOLD # Number of pages left before nextgroup DBSPACETEMP temp1dbs:temp2dbs # Default temp dbspaces # DUMP*: # The following parameters control the type of diagnostics information which # is preserved when an unanticipated error condition (assertion failure) occurs # during Dynamic S

Bernstein, Rick wrote: > > Gary, > > You may be encountering the following software defect: > > 100419 USING NVL FUNCTION ON 7.30 CAUSES 2 OR 3 SHARED MEMORY > QUERY WITHOUT NVL FUNCTION DOES NOT. > > We encountered this "bug" in IDS 7.30.UC3. It was subsequently fixed. > Check your release notes ($INFORMIXDIR/release/en_us/0333/SERVERS_7.3) > to determine if it has been fixed in your version. > If not, you should consider an upgrade or rewrite your queries. > The CASE statement can also be used to convert a null value to a non-null > value. > > Rick Bernstein > > -----Original Message----- > From: Gary Quiring > To: informix-list@iiug.org > Sent: 4/5/00 6:38 PM > Subject: dynamically allocated new shared memory segment - What is this? > > We had a pause in our Informix 7.3 system today around 5:00pm. The > system just 'froze' for almost a minute. Is there something that > needs to be tuned? This is the log during that period: > > Thanks > > Gary Quiring > > 16:44:50 Logical Log 23611 Complete. > 16:48:13 Logical Log 23612 Complete. > 16:49:25 Checkpoint Completed: duration was 12 seconds. > 16:52:56 Logical Log 23613 Complete. > 16:54:41 Checkpoint Completed: duration was 13 seconds. > 16:55:05 dynamically allocated new shared memory segment (size > 33554432) > > 16:55:44 dynamically allocated new shared memory segment (size > 33554432)> [SNIP] THese last two lines mean that two new shared memory virtual segments were allocated to support memory needs by queries needing memory for sorts, dynamic hash tables, etc. The fact that two were needed 39 seconds apart indicates that SHMADD is too small. The fact that these lines are here at all means that if they repeat, or you cannot remove them later with onmode -F, or that they come back still later if you can would indicate that their combined sizes needs to be added to SHMVIRTSIZE so the initial segment will be large enough to eliminate the need to add additional segments at runtime. The length of the pause, yes the engine pauses while the new segments are created and all of the oninits attach to them, indicates that you are running on an OS that is slow at allocating shared memory. DGUX is famous for this problem for example. -- Art S. Kagel & Family kagel@erols.com