Installation

Splunk performance issue with ver 6

splunkears
Path Finder

Facing terribly slow search time performance. Same worked fine with Splunk 5.

Job inspector shows the following:

Execution costs

Duration (seconds) Component Invocations Input count Output count

0.078   command.fields  78  911,212 911,212
184.017 command.search  78  -   911,212
0.423   command.search.index    78  -   -
0.078   command.search.calcfields   78  911,212 911,212
0.078   command.search.fieldalias   78  911,212 911,212
0   command.search.index.usec_64_512    4   -   -
0   command.search.index.usec_8_64  127 -   -
182.176 command.search.rawdata  78  -   -
0.083   command.search.kv   78  -   -
0.078   command.search.lookups  78  911,212 911,212
0.078   command.search.tags 78  911,212 911,212
0.078   command.search.typer    78  911,212 911,212
0.045   command.search.summary  78  -   -
0.018   dispatch.check_disk_usage   18  -   -
0.023   dispatch.createProviderQueue    1   -   -
0.085   dispatch.evaluate   1   -   -
0.085   dispatch.evaluate.search    1   -   -
184.037 dispatch.fetch  78  -   -
0.04    dispatch.preview    40  -   -
0.008   dispatch.readEventsInResults    1   -   -
184.023 dispatch.stream.local   78  -   -
2.303   dispatch.timeline   78  -   -
0.269   dispatch.writeStatus    119 -   -
0.039   startup.handoff

search log is showing thousands of these lines and search never completed so, finalized the search after x minutes.

11-dd-2013 09:15:07.587 INFO DispatchThread - Generating results preview took 1 ms

11-dd-2013 09:15:10.181 INFO DispatchThread - Generating results preview took 1 ms

11-dd-2013 09:15:12.591 INFO DispatchThread - Generating results preview took 1 ms

11-dd-2013 09:15:15.216 INFO DispatchThread - Generating results preview took 1 ms

From the line
182.176 command.search.rawdata 78

The 183 seconds not totaling up to the individual times spent.

Appreciate if anyone could help / shed light on this.?

Thanks.

Added more:
My indexers are version 6 as well. I've debugged this a bit further. There is not much Disc I/O but, yes the CPU spins crazy. Actually, I let the search job run in the background. This is just 30days data of size 70GB. Each day has couple of files with records more than of size 2GB. The search job completed after 45 minutes. There could something wrong with my indexing.
Here is the completed job inspector shows:

703.171 command.prestats    23,639  295,181,393 122,367
1,725.204   command.search  23,677  -   295,181,829
1,021.454   command.search.rawdata  23,638  -   -
524.957 command.search.kv   23,638  -   -
23.639  command.search.lookups  23,638  295,181,393 295,181,393
23.638  command.search.calcfields   23,638  295,181,393 295,181,393
23.638  command.search.fieldalias   23,638  295,181,393 295,181,393
10.732  command.search.summary  23,677  -   -
0   command.search.index.usec_1_8   26  -   

search log has:

11-dd-2013 hh:33:01.347 INFO loader - Detected 24 (virtual) CPUs and 193800MB RAM

11-dd-2013 hh:33:01.347 INFO loader - Maximum number of threads (approximate): 12288

11-dd-2013 hh:33:01.347 INFO loader - Arguments are: "search" "--

id=scheduler_adminlauncher_a3_at_1383438780_5" "--maxbuckets=0" "--ttl=172800" "--maxout=500000" "--maxtime=8640000" "--lookups=1" "--reduce_freq=10" "--user=admin" "--pro" "--roles=admin:can_delete:power:user"
..
..
11-dd-2013 hh:33:01.672 INFO BatchSearch - Adding bucket:mytestindex~58~0867F605-4D1D-4B32-84CD-

BBB2474E0F1B to batch search with min seek addr offset:0 and max seek addr offset:0 and bucket has time range set:0

Tags (2)
0 Karma

lokuly
New Member

We upgraded to version 6 last week. We noticed the same thing. Pre upgrade things were running well. Post upgrade CPU is maxed out and performance is terrible. No other changes were made other than the version upgrade, no modified queries, no additional data to index, no new queries. Just the version upgrade and followed by a HUGE spike in CPU.

0 Karma

splunkears
Path Finder

I tried something different. Basically, I've pre-loaded the indexed files into file-cache, so there is zero latency in IO of the indexed files. But, unfortunately, it did not succeed, as the indexed files are gzip compressed. gzip is good but slow while uncompressing.
Looking for options on how to disable compression during post-index operation.
For now, using summary indexing - sistats etc. We are ok with this approach.

0 Karma

_d_
Splunk Employee
Splunk Employee

Actually, command.search.rawdata means that the search is spending that time in CPU uncompressing rawdata. The Job Inspector numbers indicates that this is a dense search. Are your indexers version 6 as well or are they still in 5?

splunkears
Path Finder

Yes, those job inspector reports differ as they are from 2 different search jobs.
First one did not complete. Second did.

Just wanted to highlight something interesting. My h/w has 192GB memory. And, none of other system processes are consuming this memory. This search is being done on single box with search head and indexer on the same box. I'm just indexing 70GB data for a total of 30 Days. Avg size per day 2.GB

If I use Cassandra for 70GB of data, even for that matter memcache, I can keep entire 70GB in memory. And hence, I would get split second perf.

Pls. tips on. Splunk 6 perf?

0 Karma

_d_
Splunk Employee
Splunk Employee

It would help if you (1) showed what your search looks like and (2) its entire Job Inspector output. The ones you've pasted above are clearly from two different searches.

splunkears
Path Finder

Thanks for your hint on where the time is spent. The indexing is also on version 6.

0 Karma

Ayn
Legend

If you haven't already I highly recommend you to download the Splunk on Splunk app (https://apps.splunk.com/app/748/ ), it gives you lots of visibility into the health of your Splunk setup.

0 Karma

splunkears
Path Finder

Uh well, first of all it would be nice to know the actual search you're running?
The search string is just of the form -> index=myIndex
thats it.

This myIndex has 70GB of data indexed as per normal practices. No errors etc while indexing. You may be right ..as the time spent is not being shown any of the other activities of searching.. it may be just waiting to read or write etc..

I'm trying sistats etc. to see if that can help. Amazed that we see this after upgrade 😞
I might be missing something in the UI that changed significantly in ver 6.

0 Karma

Ayn
Legend

command.search.rawdata is what is spent getting the raw text of the identified events, so if this takes a long time that could imply I/O performance issues.

0 Karma

Ayn
Legend

Uh well, first of all it would be nice to know the actual search you're running?

0 Karma
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