web service timing out due to locks in database SQL Server 2008

We have a web service that times out periodically. It looks like there is a blocker/waiter happening at the same time on the db side. It also appears that the application pool fills up at the same time. We would like to monitor the lead up to the outages. What performance counters should we look for in the web service side so that we can 开发者_如何学运维run the profiler as the outage is happening to capture the conditions?

We are running IIS 7 and SQL Server 2008

Any ideas would be appreciated.

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This sounds like a loop that is pulling alot of data out of the database and storing it in memory.

It could for example take a read lock on a large table, while the data is being extracted.

I would use the SQL profiler to findout which requests are being run against the database.