How to check memory usage of SQL Server Reporting Services (SSRS)

The T-SQL code below will give you an idea of the memory used by your reporting service. This query should be executed on the "reportserver" database. Please be aware that executing this statement can take some time.

Select  Top 10
        @@Servername,
        el.TimeStart,
        el.TimeEnd,
        MemoryUsageMB
From    [ReportServer.dbo.ExecutionLog2 el
Outer Apply (
        Select  Sum(
                    Coalesce(c.value('Pagination[1]', 'int'), 0) +
                    Coalesce(c.value('Rendering[1]', 'int'), 0) +
                    Coalesce(c.value('Processing[1]', 'int'), 0)) / 1024.0 As MemoryUsageMB
        From    [ReportServer].dbo.ExecutionLog2 el2
        Cross Apply
                el2.AdditionalInfo.nodes('AdditionalInfo/EstimatedMemoryUsageKB') As b(c)
        Where   el.TimeStart Between el2.TimeStart and el2.TimeEnd
        Or      el.TimeEnd Between el2.TimeStart And el2.TimeEnd
        ) a
Order By MemoryUsageMB Desc