SAVMailThreads and SAVWriteThreads only affects Real-time Scanning
Last Updated October 23, 2013
You use the parameters SAVWriteThreads and SAVMailThreads in hopes this would speed up a manual/scheduled scan but the evidence shows that this does not improve the performance by increasing the number of threads.
The two parameters only change the scanning behavior in relation to real-time scanning and does not affect manual/scheduled scan processing.
The reason why these two parameters do not increase the performance for manual/scheduled scans is because these threads only use one thread and these get created at time to run. The parameters only affect real-time scanning for new mail routing (SAVMailThreads) through the server or new events (SAVWriteThreads) like maybe in a bulletin board database.
The reason why we have multiple threads for new mail/events is best described in an example. You have 8 mail scanning threads configured and then 4 large and 10 small emails come into the server. 4 threads get stuck processing the 4 large emails but the other 4 threads can continue to process the 10 smaller emails without waiting for those 4 threads to completely scan the 4 larger emails. This helps prevent mail from backing up too much in the mail box files and helps ensure that email gets delivered as fast as possible.
Now just because you have 8 threads it does not mean the machine processes faster because now the processing time is divided up between the threads. So a little time goes to P1 (processing large email), then P2(processing large email), then P3(processing large email), P4 (processing large email), P5 (processing small email), etc. But even though the processing is now shared the smaller messages will still complete before the larger ones and the larger ones will just take a little longer to complete. The multiple threads method works best for real-time scanning to help keep things flowing at a good rate and allows smaller stuff through without having to wait for larger stuff.
But in a manual/scheduled scan there is only one thread needed. This is because no one is waiting for these documents are at the destinations already and because this data is local and not coming in through a NIC we can scan these messages at a really high rate one behind another. A single thread going start to finish for this type of scanning will actually scan more mail in a given time period as compared to real-time scanning.
Another reason why a manual/scheduled scan processes faster is because there are less steps involved. A manual/scheduled scan opens a database once, scans everything in there and then closes the database. Whereas in real-time we are told something new has arrived and where, and then for each item we have to open that database, look for that document, scan it, then close the database.
Multiple threads work best for real-time events/documents A single thread works best for manual/scheduled scan
Imported Document ID: TECH169436
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