(Assuming 1.0* release) From the comments in cassandra.yaml # Number of simultaneous compactions to allow, NOT including # validation "compactions" for anti-entropy repair. Simultaneous # compactions can help preserve read performance in a mixed read/write # workload, by mitigating the tendency of small sstables to accumulate # during a single long running compactions. The default is usually # fine and if you experience problems with compaction running too # slowly or too fast, you should look at # compaction_throughput_mb_per_sec first. # # This setting has no effect on LeveledCompactionStrategy. # # concurrent_compactors defaults to the number of cores. # Uncomment to make compaction mono-threaded, the pre-0.8 default. #concurrent_compactors: 1
If you set it to 1 then only 1 compaction should run at a time, excluding validation. How often do you run a cleanup compaction ? They are only necessary when you perform a token move. Cheers ----------------- Aaron Morton Freelance Developer @aaronmorton http://www.thelastpickle.com On 1/02/2012, at 9:48 PM, Viktor Jevdokimov wrote: > Hi, > > When concurrent compactors are set to more then 1, it’s rare when more than 1 > compaction is running in parallel. > > Didn’t checked the source code, but it looks like when next compaction task > (any of minor, major, or cleanup) is for the same CF, it will not start in > parallel and next tasks are not checked. > > Will it be possible to check all tasks, not only the next one, to find which > of them can be started? > > This is actual especially when nightly cleanup is running, a lot of cleanup > tasks are pending, regular minor compactions are waiting until all cleanup > compactions are finished. > > > > Best regards/ Pagarbiai > > Viktor Jevdokimov > Senior Developer > > Email: viktor.jevdoki...@adform.com > Phone: +370 5 212 3063. Fax: +370 5 261 0453 > J. Jasinskio 16C, LT-01112 Vilnius, Lithuania > > > <signature-logo29.png> > > <dm-exco4823.png> > Follow: > > <tweet18be.png> > Visit our blog > > Disclaimer: The information contained in this message and attachments is > intended solely for the attention and use of the named addressee and may be > confidential. If you are not the intended recipient, you are reminded that > the information remains the property of the sender. You must not use, > disclose, distribute, copy, print or rely on this e-mail. If you have > received this message in error, please contact the sender immediately and > irrevocably delete this message and any copies. > >
