Re: Fixed time every day, redis server load suddenly high.

[Greg Andrews]

What is the size of your master's AOF file just before and just after the high server load?

The reason I ask is your master-redis.conf file has these two lines:

    auto-aof-rewrite-percentage 100
    auto-aof-rewrite-min-size 1024mb

I have an older version of Redis so I'm not familiar with those parameters.  Reading the comments explaining them, it looks like your master server's AOF file will be rewritten when it reaches 1GB (1024mb).  If your write activity is steady, the file might be reaching 1GB (and triggering a rewrite) at the same time each day.

  -Greg

On Tue, Jun 26, 2012 at 8:33 PM, PanosZhu <tjzh...@gmail.com> wrote:

Fixed time every day, redis server load suddenly high, lasting about five minutes

One master red is server and two slave redis server both occurs this phenomenon

There are no any timing tasks.

Master just only use AOF persistence, and slave did not use any data persistence strategy. Master redis config and slave redis config in the attachment.

There are server load picture.

Master-redis-server-load

Slave-redis-server-load

Any idea? Thanks beforehand for your help.

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[PanosZhu]

Hi Greg,

My master's AOF is 4G,Master daily amount of modification will not exceed 1024mb. However, this overload is a daily 10:00 occurred.So,I think this is not cause by BGREWRITEAOF.

My master redis version is 2.4.4 and slave redis version is 2.4.14.  

Best Regards!  

Panos 

在 2012年6月28日星期四UTC+8上午9时23分36秒，GregA写道：

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[Josiah Carlson]

What does top, htop, and/or iostat produce during those times?

 - Josiah

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[Aleksandar Radulovic]

Hi there,

On Wed, Jun 27, 2012 at 5:33 AM, PanosZhu <tjzh...@gmail.com> wrote:

Fixed time every day, redis server load suddenly high, lasting about five minutes

Do you by any chance have a crontab job at that time? Do you have network activity graphs that show similar spikes?

Cheers,

alex

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http://a13x.net | @a13xnet

[PanosZhu]

Hi all,

I found the Master every day in 22:04 will rewrite the dump.rdb file.

I view the redis source code found that Master will rewrite dump.rdb file when the salve first sync or reconnect to master. But what would lead to the slave disconnected and reconnect  to master every day 22:00 ?

Best Regards!  

Panos

在 2012年6月28日星期四UTC+8下午6时52分10秒，Aleksandar Radulovic写道：

[Greg Andrews]

PanosZhu wrote:

But what would lead to the slave disconnected and reconnect  to master every day 22:00 ?

There can be lots of reasons.  The master's logfile should show you which slave is connecting and causing the file i/o activity.  Once you know that, you can look in the slave's logfile for more information.

Your long-running slaves might lose their connections to the master at 22:00.  Or some other cron job might be attaching a slave to perform backups.  We can't really know.

The logfile for the master and the logfiles for the slaves should give you the best hints about what is happening.

  -Greg

[PanosZhu]

Hi Greg,

Thank you very much.

I think I found the reason.Master on 10:00 have a BGREWRITEAOF timing task, BGREWRITEAOF will rewrite the aof file and the dump file.

Thank everyone.

Best regards,

Panos

在 2012年6月29日星期五UTC+8上午11时51分35秒，GregA写道：

[Greg Andrews]

I don't see any configuration like that in the master-redis.conf file you posted.  Is it a cron job that connects to the master and issues a bgrewriteaof command?

  -Greg

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[PanosZhu]

Hi Greg,

I have a shell cron job, the command is ./server-cli BGREWRITEAOF.

But, why BGREWRITEAOF will rewrite dump file?

在 2012年6月29日星期五UTC+8下午12时42分58秒，GregA写道：

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