performance degradation with burst connects
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Key: CORE-4650
URL: http://tracker.firebirdsql.org/browse/CORE-4650
Project: Firebird Core
Issue Type: Bug
Components: Engine
Affects Versions: 3.0 Beta 1
Environment: Win7 64Bit WI-T3.0.0.31374 Firebird 3.0 Beta 1, Apache
2.4, Firefox 34, d3.js/XHR
Reporter: Volker Rehn
test scenario: web application sending a dozen or so burst requests
asynchronously to web server / firebird at a time. The requests are only
milliseconds apart, and each of them only asks for a small amount of blob data
(< 100 B - up to a few 100 KB, but data volume doesn't play a role here). From
a web server/firebird perspective, they all come with the same connect data,
host/port:db-alias, user, originating client are the same. Requests/connections
are all short-lived, they ask for data and disconnect again, within
milliseconds.
With Firebird alpha 2, a test page needs 2 seconds to fully load, with beta 1,
it needs 4 seconds. Other test pages similar.
BUT, and this is the esoteric part, and perhaps the key to solve this, if some
desktop application (eg Flamerobin) simply holds a *constant* connection to the
database while the test page is run, the test page again loads in 2 seconds or
even less. All of this reproducible, no cache effects. Disconnect the
application (ending the constant connection) and the web page runs slow.
Connect Flamerobin and the test page is fast.
What happens is that some requests of the test page, not all of them, but
always the same, are getting delayed, typically and reproducible for around 1
second. I verified that the delay is not due to the database generating the
data, but due to its delivery by the database server.
It looks like it has to do with Firebird beta's connection handling.
Connections coming through the web server are short-lived, maybe Apache does
some pooling, I don't know. As if Firebird would try to cleanup or release or
reallocate ressources after it handled two or three of those fast connections.
Or it simply takes a break for a second ;-). But only if there is no constant
connection at the same time.
Hope this makes sense to you.
С наступающим Новым годом
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