The onstat -g ath command prints information about all threads.
The following table summarizes the threads that Enterprise Replication uses. You can use this information about threads when you evaluate memory use. For more information, see the utilities chapter of the IBM Informix Administrator's Reference.
| Number of Threads | Thread Name | Thread Description |
|---|---|---|
| 1 | ddr_snoopy | Performs physical I/O from logical log, verifies potential replication, and sends applicable log-record entries to Enterprise Replication |
| 1 | preDDR | Runs during queue recovery to monitor the log and sets blockout mode if the log position advances too far before replication resumes |
| 1 | CDRGfan | Receives log entries and passes entries to evaluator thread |
| n | CDRGevaln | Evaluates log entry to determine if it should be replicated
(n is the number of evaluator threads specified by
CDR_EVALTHREADS)
This thread also performs transaction compression on the receipt of COMMIT WORK and queues completed replication messages. |
| 1 per large transaction | CDRPager | Performs the physical IO for the temporary smart large
object that holds paged transaction records
Grouper paging is activated for a transaction when its size is 10 percent of the value of SHMVIRTSIZE or CDR_QUEUEMEM or when it includes more than 100,000 records. |
| 1 | CDRCparse | Parses all SQL statements for replicate definitions |
| 1 per connection | CDRNsTnCDRNsAn | Sending thread for site |
| 1 per connection | CDRNrn | Receiving thread for site |
| 2...n | CDRACK_n | Accepts acknowledgments from site
At least 2, up to a maximum of the number of active connections |
| # CPUs... | CDRD_n | Replays transaction on the target system (DataSync thread)
At least one thread is created for each CPU virtual processor (VP). The maximum number of threads is 4*(number of CPU VPs). |
| 1 | CDRSchedMgr | Schedules internal Enterprise Replication events |
| 0 or 1 | CDRM_Monitor | Monitors and adjusts DataSync performance for optimum performance (on the target) |
| 0 or 1 | CDRDTCleaner | Deletes (cleans) rows from the deleted rows shadow table when they are no longer needed |