Bug 19595 - Seems Path.GetTempFilename as issues closing it's file handles
Summary: Seems Path.GetTempFilename as issues closing it's file handles
Status: RESOLVED NOT_REPRODUCIBLE
Alias: None
Product: Class Libraries
Classification: Mono
Component: mscorlib ()
Version: 3.2.x
Hardware: PC Linux
: --- normal
Target Milestone: Untriaged
Assignee: Marek Safar
URL:
Depends on:
Blocks:
 
Reported: 2014-05-07 11:11 UTC by Svein Arne Ackenhausen
Modified: 2014-05-08 04:19 UTC (History)
3 users (show)

Tags:
Is this bug a regression?: ---
Last known good build:

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Status:
RESOLVED NOT_REPRODUCIBLE

Description Svein Arne Ackenhausen 2014-05-07 11:11:45 UTC
Getting there error below when using GetTempFilename a lot. Every occurrence of this bug has shown this stack trace so it's likely that GetTempFilename is involved.

Unhandled Exception:
System.IO.IOException: Too many open files
  at System.IO.FileStream..ctor (System.String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, Boolean anonymous, FileOptions options) [0x00000] in <filename unknown>:0 
  at (wrapper remoting-invoke-with-check) System.IO.FileStream:.ctor (string,System.IO.FileMode,System.IO.FileAccess,System.IO.FileShare,int,bool,System.IO.FileOptions)
  at System.IO.Path.GetTempFileName () [0x00000] in <filename unknown>:0 
[ERROR] FATAL UNHANDLED EXCEPTION: System.IO.IOException: Too many open files
  at System.IO.FileStream..ctor (System.String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, Boolean anonymous, FileOptions options) [0x00000] in <filename unknown>:0 
  at (wrapper remoting-invoke-with-check) System.IO.FileStream:.ctor (string,System.IO.FileMode,System.IO.FileAccess,System.IO.FileShare,int,bool,System.IO.FileOptions)
  at System.IO.Path.GetTempFileName () [0x00000] in <filename unknown>:0
Comment 1 Jonathan Pryor 2014-05-07 11:29:45 UTC
Ouch: https://github.com/mono/mono/blob/8d024395/mcs/class/corlib/System.IO/Path.cs#L466

Quick looks suggests that if we execute the loop on lines 475-492 more than once, we'll leak file descriptors (`f` is not disposed until line 494).
Comment 2 Marek Safar 2014-05-08 04:19:23 UTC
I cannot see anything wrong with GetTempFileName. 

Simple tests shows nothing too. 

		while (true) {
			Console.WriteLine (Path.GetTempFileName ());
		}

There is most likely leak somewhere when you get this exception but GetTempFileName just exposes it because it's called frequently in your code