[MB-4418] Allow disk write queue cap to be modified at runtime Created: 10/Nov/11  Updated: 16/May/12  Resolved: 10/May/12

Status: Resolved
Project: Couchbase Server
Component/s: couchbase-bucket
Affects Version/s: 1.8.0
Fix Version/s: 1.8.1
Security Level: Public

Type: Improvement Priority: Major
Reporter: Perry Krug Assignee: Mike Wiederhold
Resolution: Fixed Votes: 0
Labels: 1.8.0-release-notes, 1.8.1-release-notes
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Comment by Thuan Nguyen [ 29/Dec/11 ]
Integrated in github-ep-engine-2-0 #131 (See [http://qa.hq.northscale.net/job/github-ep-engine-2-0/131/])
Comment by Perry Krug [ 17/Jan/12 ]
This behavior needs to be changed.

The current method is to use '-1' to disable the cap completely, but there are a variety of problems with that including the fact that cbflushctl can't be used to actually set a -1:
[perry@Membase1 ~]$ /opt/couchbase/bin/cbflushctl localhost:11210 set tap_throttle_queue_cap "-1"
usage: cbflushctl [options]

cbflushctl: error: no such option: -1

Please change it so that a value of '0' disables the cap
Comment by Mike Wiederhold [ 17/Jan/12 ]
We would rather fix cbflushctl in this case since it should be able to accept negative numbers. Setting the tap_throttle_queue_cap to -1 works in ep-engine.
Comment by Perry Krug [ 17/Jan/12 ]
I also tried to set it at the Erlang level with:
wget -O- --user=<user> --password=<pass> --post-data='ns_bucket:update_bucket_props("default", [{extra_config_string, "tap_throttle_queue_cap=-1"}]).' http://localhost:8091/diag/eval

And the memcached process failed to start with this message in the logs;

[user:info] [2012-01-17 13:53:41] [ns_1@<0.8646.1>:ns_port_server:handle_info:96] Port server memcached on node 'ns_1@' exited with status 139. Restarting. Messages: Invalid entry, Key: <tap_throttle_queue_cap> Value: <-1>

Since this works fine with a value other than -1, I assumed the problem was not just with cbflushctl...
Comment by Steve Yen [ 19/Jan/12 ]
Reassigning to Jin, regarding the -1.
Comment by Farshid Ghods (Inactive) [ 17/Mar/12 ]
we should also add this to documentation.
adding MC to the ticket
Comment by Thuan Nguyen [ 16/May/12 ]
Integrated in github-ep-engine-2-0 #282 (See [http://qa.hq.northscale.net/job/github-ep-engine-2-0/282/])
    MB-4418: tap_throttle_queue_cap in cbflushctl takes 'infinite' argument (Revision 7c4203378ab21f598247b88eefddf7d55e0bf124)

     Result = SUCCESS
Mike Wiederhold :
Files :
* management/cbflushctl
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