How to create gcdump from linux core dump? (linux-arm core dump)

[michaldobrodenka]

I have an app on linux-arm, machine with only 512MB RAM and very small flash disk. My app is self contained, and sometimes has leaks. I don't have there dotnet-gcdump.

But I have core dump from linux. Is it possible to make gcdump from coredump? So I will know what objects are leaking?

I tried it with PerfView - Memory->Take Heap snapshot from Dump, but this is the result:

Completed: Dumping GC Heap to c:\work\issues\Kolisky\dumpgc.core   (Elapsed Time: 6.488 sec)
Error: HeapDump failed with exit code 1
Started: Dumping GC Heap to c:\work\issues\Kolisky\dumpgc
[Extracting gcHeap from process dump c:\work\issues\Kolisky\dump.core  to c:\work\issues\Kolisky\dumpgc.gcdump]
Starting dump at 1/12/2023 10:52:34 AM
********** TRYING TO OPEN THE DUMP AS 64 BIT ************
set _NT_SYMBOL_PATH=;SRV*C:\Users\mixal\AppData\Local\Temp\SymbolCache*https://msdl.microsoft.com/download/symbols;SRV*C:\Users\mixal\AppData\Local\Temp\SymbolCache*https://nuget.smbsrc.net;SRV*C:\Users\mixal\AppData\Local\Temp\SymbolCache*https://referencesource.microsoft.com/symbols
Exec: "C:\Users\mixal\AppData\Roaming\PerfView\VER.2021-05-18.13.31.45.906\amd64\HeapDump.exe" /processDump  /MaxDumpCountK=250 "c:\work\issues\Kolisky\dump.core " "c:\work\issues\Kolisky\dumpgc.gcdump"
Creating heap dump c:\work\issues\Kolisky\dumpgc.gcdump from process dump c:\work\issues\Kolisky\dump.core.
HeapDump Error (-2147024809): Microsoft.Diagnostics.Runtime.ClrDiagnosticsException: Could not load crash dump, HRESULT: 0x80070057
   at Microsoft.Diagnostics.Runtime.DbgEngDataReader..ctor(String dumpFile)
   at Microsoft.Diagnostics.Runtime.DataTarget.LoadCrashDump(String fileName)
   at GCHeapDumper.InitializeClrRuntime(String processDumpFile, DataTarget& target, ClrRuntime& runtime)
   at GCHeapDumper.DumpHeapFromProcessDump(String processDumpFile)
   at Program.MainWorker(String[] args)


********** TRYING TO OPEN THE DUMP AS 32 BIT ************
set _NT_SYMBOL_PATH=;SRV*C:\Users\mixal\AppData\Local\Temp\SymbolCache*https://msdl.microsoft.com/download/symbols;SRV*C:\Users\mixal\AppData\Local\Temp\SymbolCache*https://nuget.smbsrc.net;SRV*C:\Users\mixal\AppData\Local\Temp\SymbolCache*https://referencesource.microsoft.com/symbols
Exec: "C:\Users\mixal\AppData\Roaming\PerfView\VER.2021-05-18.13.31.45.906\x86\HeapDump.exe" /processDump /MaxDumpCountK=250 "c:\work\issues\Kolisky\dump.core " "c:\work\issues\Kolisky\dumpgc.gcdump"
Creating heap dump c:\work\issues\Kolisky\dumpgc.gcdump from process dump c:\work\issues\Kolisky\dump.core.
HeapDump Error (-2147024809): Microsoft.Diagnostics.Runtime.ClrDiagnosticsException: Could not load crash dump, HRESULT: 0x80070057
   at Microsoft.Diagnostics.Runtime.DbgEngDataReader..ctor(String dumpFile)
   at Microsoft.Diagnostics.Runtime.DataTarget.LoadCrashDump(String fileName)
   at GCHeapDumper.InitializeClrRuntime(String processDumpFile, DataTarget& target, ClrRuntime& runtime)
   at GCHeapDumper.DumpHeapFromProcessDump(String processDumpFile)
   at Program.MainWorker(String[] args)


Completed: Dumping GC Heap to c:\work\issues\Kolisky\dumpgc   (Elapsed Time: 2.438 sec)
Error: HeapDump failed with exit code 1

Is it supposed to work? linux-arm core dump on windows?

Thank you!

[tommcdon]

Hello @michaldobrodenka! Just for your awareness, we have a tutorial on debugging memory leaks. Note that the built-in Linux coredump feature may not contain all of the data needed for investigation. We suggest collecting Linux dumps using the dotnet-dump global tool. The dump can be analyzed on the Linux machine with dotnet-dump, or the dump can be copied to Windows and analyzed directly using Visual Studio (File->Open the dump, then click on Debug Managed Memory), windbg, or the dotnet-dump tool as well.

[michaldobrodenka]

Thank you for the answer! Normal dotnet-gcdump is not an option, it is minimalistic linux, I can't get there dotnet, sdk & tools. I've compiled dotnet-gcdump from modified sources, as self contained. When I run it for testing, it works. But when I run it when memory is getting low - my process including my modified dotnet-gcdump is killed by oom killer :)

But thank to links provided, I've found, that I can create dumps with heap info with createdump and analyze it on another machine.