From user-return-23885-apmail-cassandra-user-archive=cassandra.apache.org@cassandra.apache.org Wed Feb 1 19:51:52 2012 Return-Path: X-Original-To: apmail-cassandra-user-archive@www.apache.org Delivered-To: apmail-cassandra-user-archive@www.apache.org Received: from mail.apache.org (hermes.apache.org [140.211.11.3]) by minotaur.apache.org (Postfix) with SMTP id 6EE0D9C39 for ; Wed, 1 Feb 2012 19:51:52 +0000 (UTC) Received: (qmail 15147 invoked by uid 500); 1 Feb 2012 19:51:49 -0000 Delivered-To: apmail-cassandra-user-archive@cassandra.apache.org Received: (qmail 15042 invoked by uid 500); 1 Feb 2012 19:51:48 -0000 Mailing-List: contact user-help@cassandra.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: user@cassandra.apache.org Delivered-To: mailing list user@cassandra.apache.org Received: (qmail 15034 invoked by uid 99); 1 Feb 2012 19:51:48 -0000 Received: from athena.apache.org (HELO athena.apache.org) (140.211.11.136) by apache.org (qpsmtpd/0.29) with ESMTP; Wed, 01 Feb 2012 19:51:48 +0000 X-ASF-Spam-Status: No, hits=2.2 required=5.0 tests=HTML_MESSAGE,RCVD_IN_DNSWL_NONE,SPF_PASS X-Spam-Check-By: apache.org Received-SPF: pass (athena.apache.org: local policy) Received: from [208.113.200.5] (HELO homiemail-a83.g.dreamhost.com) (208.113.200.5) by apache.org (qpsmtpd/0.29) with ESMTP; Wed, 01 Feb 2012 19:51:42 +0000 Received: from homiemail-a83.g.dreamhost.com (localhost [127.0.0.1]) by homiemail-a83.g.dreamhost.com (Postfix) with ESMTP id 414DA5E074 for ; Wed, 1 Feb 2012 11:51:21 -0800 (PST) DomainKey-Signature: a=rsa-sha1; c=nofws; d=thelastpickle.com; h=from :mime-version:content-type:subject:date:in-reply-to:to :references:message-id; q=dns; s=thelastpickle.com; b=GhzbAlBNEa RmbaR9WtwL5Qe2V+qGkYbItAPc1rTndGBgSTty8X1DVPYIDJfDt4MvsTcMbFfgUK TpeWsHGMTLV+pPv/N5cuVnVyzQdLRSWGgK8Nqia4uq6EjgYanyeDO70ixPBiSu5Y Sz0iTUItjxIAbBK7s/VdLmom6dKXXzT34= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=thelastpickle.com; h=from :mime-version:content-type:subject:date:in-reply-to:to :references:message-id; s=thelastpickle.com; bh=zRJwzZzDvJPCFPD4 088FlIo/IwE=; b=ln9qw+WgQ/W3VvEzd708WJ79tlMoP592opuDKuKfpM4UdzyM Q8/fbEHOsDmJXA8of+kG1qCxd1zEMicbBTFQthfVXhLU/hbitAUn2ETvrAz1Ftko mWPEzD51KEq9keIM+z1SjvNhTX6PTrW0zsCoy42SWZjWYA7v+Bc8On/pG/Q= Received: from 202-126-206-194.vectorcommunications.net.nz (unknown [202.126.206.194]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (No client certificate requested) (Authenticated sender: aaron@thelastpickle.com) by homiemail-a83.g.dreamhost.com (Postfix) with ESMTPSA id 7DF3C5E06E for ; Wed, 1 Feb 2012 11:51:20 -0800 (PST) From: aaron morton Mime-Version: 1.0 (Apple Message framework v1251.1) Content-Type: multipart/alternative; boundary="Apple-Mail=_4D881677-E02A-4078-8837-2D1BAB87F972" Subject: Re: Consurrent compactors Date: Thu, 2 Feb 2012 08:51:18 +1300 In-Reply-To: <2C85E14562B39345BCCAD90B8E7955C9085DF0@DKEXC001.adform.com> To: user@cassandra.apache.org References: <2C85E14562B39345BCCAD90B8E7955C9085DF0@DKEXC001.adform.com> Message-Id: <69B2567D-6437-470F-935B-7AB882ABA6BF@thelastpickle.com> X-Mailer: Apple Mail (2.1251.1) --Apple-Mail=_4D881677-E02A-4078-8837-2D1BAB87F972 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=windows-1252 (Assuming 1.0* release) =46rom 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.=20 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, > =20 > When concurrent compactors are set to more then 1, it=92s rare when = more than 1 compaction is running in parallel. > =20 > Didn=92t 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. > =20 > Will it be possible to check all tasks, not only the next one, to find = which of them can be started? > =20 > 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. > =20 > =20 > =20 > Best regards/ Pagarbiai > =20 > Viktor Jevdokimov > Senior Developer > =20 > Email: Viktor.Jevdokimov@adform.com > Phone: +370 5 212 3063. Fax: +370 5 261 0453 > J. Jasinskio 16C, LT-01112 Vilnius, Lithuania > =20 > =20 > >=20 > > Follow: >=20 > > Visit our blog >=20 > 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. >=20 >=20 --Apple-Mail=_4D881677-E02A-4078-8837-2D1BAB87F972 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=windows-1252 (Assuming 1.0* release)
=46rom 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

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=92s = rare when more than 1 compaction is running in = parallel.
 
Didn=92t 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.
 
 
<= /table>


= --Apple-Mail=_4D881677-E02A-4078-8837-2D1BAB87F972--

 
Best regards/ = Pagarbiai
Viktor = Jevdokimov
Senior = Developer
J. Jasinskio 16C, LT-01112 Vilnius, = Lithuania