Tools Tips and Tricks #10: Caching PDB files locally


When you are debugging a SQL Server memory dump, you would need the PDB files associated with the sqlservr.exe that you are debugging to get the call stacks. The PDB files can be downloaded from the Microsoft Symbol Server. Paul Randal [Blog | Twitter] in a previous blog post showed how to do this using symchk.exe. If you want to download symbols for multiple EXEs then you either need to create a script file or you could use the method mentioned below provided you have a dump file that you are interested in.

Today I am going to explain how to download PDB files using CDB (Command Line Debugger) and command script file. The first ingredient for this is a memory dump file (.mdmp or .dmp). Once you have the dump and the Windows Debugging Tools installed on your local machine, you use the following command to cache the symbols to a local folder:

C:\Program Files\Debugging Tools for Windows (x64)>cdb -y srv*D:\PublicSymbols*http://msdl.microsoft.com/download/symbols -z “D:\SQLDump0134.mdmp” -cfr “D:\ExecuteSymbolFetch.txt” > D:\DebuggingExample.txt

The –y parameter specifies the local folder into which the symbols need to be cached and the –z parameter is the path to the memory dump file. The –cfr parameter takes the path to the script file which contains the script file to be executed. The contents of my script file are:

!sym noisy
.reload /f
lmvm sqlservr
qd

When you look into the DebuggingExample.txt file once the download has completed, you will find the output of the lmvm command which will show you that the PDB file was cached locally:

0:031> lmvm sqlservr
sqlservr   (pdb symbols)          d:\publicsymbols\sqlservr.pdb\389EF554D94A4947846D85FCDC4233382\sqlservr.pdb

Alternatively, you could load the dump using WinDBG and then using the commands from the script file mentioned above to cache the symbols. You would need to set the symbol file path using File->Symbol File Path or CTRL+S option or using the debugger command .sympath. Once that is done, you can executed .reload /f to download the PDB files from the Microsoft Symbol Server. This is helpful when you need symbol files while capturing certain debugging diagnostic data like generating the XML file with the callstacks from a Process Monitor trace as shown here or if you want to perform an analysis using the existing scripts provided with the Debug Diagnostic tool.

Debugging Download location:
64-bit Debugging Tools
32-bit Debugging Tools

References:
Using Script files for Windows Debugger
Command line CDB options

Tools, Debugging, Tools Tips and Tricks

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2 thoughts on “Tools Tips and Tricks #10: Caching PDB files locally

  1. Pingback: learnSQL.99hosting.info » Blog Archive » Tools Tips and Tricks #10: Caching PDB files locally …

  2. Pingback: Tools Tips and Tricks: Round-up « TroubleshootingSQL

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