Handling concurrent requests

[girishkc]

I have a web application built using PHP and MySQL. Now the database is hitting the red line due to the load. I am trying to use phpfastcache to store set of data into redis and reduce the load on the DB. The data set is from multiple tables and may take up to 15 seconds to fetch. But I am getting requests from client every 2-3 seconds. So there can be 5-6 requests while the cache is building. That is when the existing cache is expired and new one is getting build.

These requests are again trying to build the cache, that will add up to the cache building time.

Is there any way to workaround this problem?

Thanks :)

[Geolim4]

Hello, I'm currently on vacations, I will come back to you in a week :) Cheers, Georges Le 20 févr. 2017 2:59 PM, "Girish" <notifications@github.com> a écrit :

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I have a web application built using PHP and MySQL. Now the database is hitting the red line due to the load. I am trying to use phpfastcache to store set of data into redis and reduce the load on the DB. The data set is from multiple tables and may take up to 15 seconds to fetch. But I am getting requests from client every 2-3 seconds. So there can be 5-6 requests while the cache is building. That is when the existing cache is expired and new one is getting build. These requests are again trying to build the cache, that will add up to the cache building time. Is there any way to workaround this problem? Thanks :) — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#433>, or mute the thread <https://github.com/notifications/unsubscribe-auth/ABRTZzsWCG7EsZKUtyox-1w-zIZMNGYMks5reZxcgaJpZM4MGNc0> .

[Geolim4]

Hello,

I think it's a design issue that we cannot fix at all:

We could set a "flag" with a temporary value to store the item as is, but if a concurrent request get the item it wont get the expected value such an array , but a boolean flag that you can't deal with :/

My idea is to work with a cron that will rebuild the cache Item regularly or you can build a batch system.

Cheers,
Georges

[Geolim4]

This remind me something like this i read recently on Doctrine project called "Cache Slams":
http://doctrine-orm.readthedocs.io/projects/doctrine-orm/en/latest/reference/caching.html#cache-slams

[Geolim4]

I'm working on a prototype and I'm seeking for a tester, would you help me to test this out ?
Thanks :)

[girishkc]

Definitely.
Let me know how can I help.

[Geolim4]

Please test the V6 from the latest commits...
The latest commits introduces a Batch system that force concurrent request to wait.

[Geolim4]

In wrote a Wiki about this:
https://github.com/PHPSocialNetwork/phpfastcache/wiki/%5BV6%CB%96%5D-Dealing-with-cache-slams

[Geolim4]

Hello @girishkc can you give me a feedback about this ?
It would be very appreciated :-)

Cheers,
Georges

[Geolim4]

The issue has been fixed, thanks you for your contribution 👍

Geolim4