Distributed lock management

[Simon Goldschmidt]

Since moving to a clustered environment, I noticed that <cflock scope="session"> is only aware of locks on the local node. Google turns up a solution using Redis, but I wondered if anyone had suggestions from their experience.

We use a datasource for session storage and include <cfset this.sessioncluster=true> in our Application.cfc.

If we're happy to throw an error in the case of a locking conflict, could we implement our own solution by declaring a session variable, checking to see if that variable exists before performing the code in the <cflock> block, then deleting the variable at the end of the block?

Thanks... Simon

[Harry Klein]

Hi Simon,

 

so I guess you found this Github project from Ben Nadel https://github.com/bennadel/CFRedlock?

I can definitely recommend it, works great in our projects.

 

Cheers,

Harry

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[Simon Goldschmidt]

The alternative we're looking at is to use the database to manage the locking. We replace the <cflock> with the following:

<cftransaction>

<cfquery name="sessionlock" datasource="mydatasource">

  update customer set address=address where customer='#session.customerid#'

</cfquery>

block of locked code goes here

</cftransaction>

The update doesn't do anything but lock the rows of the database relevant to the session, so this has the same effect as <cflock scope="session">

Simon

[Michael van Leest]

@Simon: that example will work with a single server. If you have multiple servers, this is not thread safe. You might want to create a stored procedure and use a transaction in that procedure to make it thread safe for multiple webservers.

Hope that will work for you.

Mike

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