OPAC Can Cause Proliferation of Connected CStore Drones

[Jason Stephenson]

EG version: 2.7.1 (affects all versions with TPAC)
Rest is irrelevant

When a patrons views their current circulations in the My Account section of the TPAC, a transaction is begun to retrieve the list out of the database and avoid the cache. This transaction opens a connected session to a cstore drone. The connection is never closed causing the cstore drone to remain unusable until the session timeout time arrives (6 seconds by default).

On a busy server, this can lead to a proliferation of cstore drones doing next to nothing. In extreme cases, it can lead to the maximum number of cstore drones being in service and a failure to create more. If this happens during a particularly busy time of the day, when libraries are doing pull lists or other cstore-intensive activities, the load on the server will spike as ejabberd and other services try to respond while cstore drones are mostly ignoring connections. This has lead to the need to restart services on at least one production system.

There is potentially a similar problem in the getit_results function of the EGKPacLoader as well.

I pushed a branch, user/dyrcona/lp1415898_opac_xact_fix, to the working repo with two commits. d1c341674bbde863062726421d60d54c53eab74b fixes the issue in the My Account area of the OPAC, and 5312dd31fcd0812f90cbafaf6fa6de8ab39a1b23 fixes the problem in the KPAC. I figured I'd split it over two commits, since not everyone uses the KPAC.

Links:

http://git.evergreen-ils.org/?p=working/Evergreen.git;a=shortlog;h=refs/heads/user/dyrcona/lp1415898_opac_xact_fix

http://git.evergreen-ils.org/?p=working/Evergreen.git;a=commitdiff;h=d1c341674bbde863062726421d60d54c53eab74b

http://git.evergreen-ils.org/?p=working/Evergreen.git;a=commitdiff;h=5312dd31fcd0812f90cbafaf6fa6de8ab39a1b23

[Jason Stephenson (jstephenson)]

Oh, and I should mention that we have been running the above code in production since Tuesday, 2015-01-27.

[Bill Erickson (berick)]

Confirmed and tested. Solves the problem as expected. Merged to 2.6, 2.7, and master.