Process.WaitForExit(Int32) sometimes throws AggregateException on macOS #85717

Metalnem · 2023-05-03T16:27:28Z

Description

Process.WaitForExit(Int32) overload sometimes unexpectedly throws AggregateException (with TaskCanceledException inside). The issue can be reliably reproduced on macOS, but it doesn't seem to be happening on Windows.

Reproduction Steps

The following code snippet will trigger the issue on macOS (usually after several seconds, but sometimes it will take 1-2 minutes):

for (int i = 0; ; ++i)
{
    try
    {
        var process = Process.GetCurrentProcess();
        process.WaitForExit(10);
    }
    catch
    {
        Console.WriteLine($"{nameof(Process.WaitForExit)} failed in iteration {i}");
        throw;
    }
}

It doesn't matter which process instance was used (that is, you can use any active process and call Process.GetProcessById).

Expected behavior

Process.WaitForExit(Int32) shouldn't throw AggregateException.

Actual behavior

Process.WaitForExit(Int32) throws AggregateException on macOS (but not on Windows):

WaitForExit failed in iteration 979
Unhandled exception. System.AggregateException: One or more errors occurred. (A task was canceled.)
 ---> System.Threading.Tasks.TaskCanceledException: A task was canceled.
   at System.Threading.Tasks.Task.GetExceptions(Boolean includeTaskCanceledExceptions)
   at System.Threading.Tasks.Task.ThrowIfExceptional(Boolean includeTaskCanceledExceptions)
   at System.Threading.Tasks.Task.Wait(Int32 millisecondsTimeout, CancellationToken cancellationToken)
   at System.Diagnostics.ProcessWaitState.WaitForExit(Int32 millisecondsTimeout)
   at System.Diagnostics.Process.WaitForExitCore(Int32 milliseconds)
   at System.Diagnostics.Process.WaitForExit(Int32 milliseconds)
   at WaitForExit.Program.Main(String[] args) in /Users/Metalnem/Temp/WaitForExit/Program.cs:line 14
--- End of stack trace from previous location ---

   --- End of inner exception stack trace ---
   at System.Threading.Tasks.Task.ThrowIfExceptional(Boolean includeTaskCanceledExceptions)
   at System.Threading.Tasks.Task.Wait(Int32 millisecondsTimeout, CancellationToken cancellationToken)
   at System.Diagnostics.ProcessWaitState.WaitForExit(Int32 millisecondsTimeout)
   at System.Diagnostics.Process.WaitForExitCore(Int32 milliseconds)
   at System.Diagnostics.Process.WaitForExit(Int32 milliseconds)
   at WaitForExit.Program.Main(String[] args) in /Users/Metalnem/Temp/WaitForExit/Program.cs:line 14

Regression?

The issue is present at least in .NET 6.0, 7.0, and 8.0.

Known Workarounds

No response

Configuration

.NET SDK:
 Version:   8.0.100-preview.3.23178.7
 Commit:    e300b0e1e6

Runtime Environment:
 OS Name:     Mac OS X
 OS Version:  10.15
 OS Platform: Darwin
 RID:         osx.10.15-x64
 Base Path:   /usr/local/share/dotnet/sdk/8.0.100-preview.3.23178.7/

.NET workloads installed:
There are no installed workloads to display.

Host:
  Version:      8.0.0-preview.3.23174.8
  Architecture: x64
  Commit:       47bad717bd

.NET SDKs installed:
  6.0.302 [/usr/local/share/dotnet/sdk]
  7.0.102 [/usr/local/share/dotnet/sdk]
  8.0.100-preview.3.23178.7 [/usr/local/share/dotnet/sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.App 6.0.7 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 7.0.2 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 8.0.0-preview.3.23177.8 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 6.0.7 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 7.0.2 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 8.0.0-preview.3.23174.8 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]

Other information

No response

The text was updated successfully, but these errors were encountered:

ghost · 2023-05-03T16:27:36Z

Tagging subscribers to this area: @dotnet/area-system-diagnostics-process
See info in area-owners.md if you want to be subscribed.

Issue Details

Description

Process.WaitForExit(Int32) overload sometimes unexpectedly throws AggregateException (with TaskCanceledException inside). The issue can be reliably reproduced on macOS, but it doesn't seem to be happening on Windows.

Reproduction Steps

The following code snippet will trigger the issue on macOS (usually after several seconds, but sometimes it will take 1-2 minutes):

for (int i = 0; ; ++i)
{
    try
    {
        var process = Process.GetCurrentProcess();
        process.WaitForExit(10);
    }
    catch
    {
        Console.WriteLine($"{nameof(Process.WaitForExit)} failed in iteration {i}");
        throw;
    }
}

It doesn't matter which process instance was used (that is, you can use any active process and call Process.GetProcessById).

Expected behavior

Process.WaitForExit(Int32) shouldn't throw AggregateException.

Actual behavior

Process.WaitForExit(Int32) throws AggregateException on macOS (but not on Windows):

WaitForExit failed in iteration 979
Unhandled exception. System.AggregateException: One or more errors occurred. (A task was canceled.)
 ---> System.Threading.Tasks.TaskCanceledException: A task was canceled.
   at System.Threading.Tasks.Task.GetExceptions(Boolean includeTaskCanceledExceptions)
   at System.Threading.Tasks.Task.ThrowIfExceptional(Boolean includeTaskCanceledExceptions)
   at System.Threading.Tasks.Task.Wait(Int32 millisecondsTimeout, CancellationToken cancellationToken)
   at System.Diagnostics.ProcessWaitState.WaitForExit(Int32 millisecondsTimeout)
   at System.Diagnostics.Process.WaitForExitCore(Int32 milliseconds)
   at System.Diagnostics.Process.WaitForExit(Int32 milliseconds)
   at WaitForExit.Program.Main(String[] args) in /Users/Metalnem/Temp/WaitForExit/Program.cs:line 14
--- End of stack trace from previous location ---

   --- End of inner exception stack trace ---
   at System.Threading.Tasks.Task.ThrowIfExceptional(Boolean includeTaskCanceledExceptions)
   at System.Threading.Tasks.Task.Wait(Int32 millisecondsTimeout, CancellationToken cancellationToken)
   at System.Diagnostics.ProcessWaitState.WaitForExit(Int32 millisecondsTimeout)
   at System.Diagnostics.Process.WaitForExitCore(Int32 milliseconds)
   at System.Diagnostics.Process.WaitForExit(Int32 milliseconds)
   at WaitForExit.Program.Main(String[] args) in /Users/Metalnem/Temp/WaitForExit/Program.cs:line 14

Regression?

The issue is present at least in .NET 6.0, 7.0, and 8.0.

Known Workarounds

No response

Configuration

.NET SDK:
 Version:   8.0.100-preview.3.23178.7
 Commit:    e300b0e1e6

Runtime Environment:
 OS Name:     Mac OS X
 OS Version:  10.15
 OS Platform: Darwin
 RID:         osx.10.15-x64
 Base Path:   /usr/local/share/dotnet/sdk/8.0.100-preview.3.23178.7/

.NET workloads installed:
There are no installed workloads to display.

Host:
  Version:      8.0.0-preview.3.23174.8
  Architecture: x64
  Commit:       47bad717bd

.NET SDKs installed:
  6.0.302 [/usr/local/share/dotnet/sdk]
  7.0.102 [/usr/local/share/dotnet/sdk]
  8.0.100-preview.3.23178.7 [/usr/local/share/dotnet/sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.App 6.0.7 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 7.0.2 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 8.0.0-preview.3.23177.8 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 6.0.7 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 7.0.2 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 8.0.0-preview.3.23174.8 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]

Other information

No response

Author:	Metalnem
Assignees:	-
Labels:	`area-System.Diagnostics.Process`, `untriaged`
Milestone:	-

skyoxZ · 2023-05-06T03:37:33Z

runtime/src/libraries/System.Diagnostics.Process/src/System/Diagnostics/ProcessWaitState.Unix.cs

Line 551 in e61e022

}, cancellationToken);

It seems that Task.Run could be unexpectedly cancelled by this token.

In such a situation the delegate doesn't run and let the ProcessWaitState instance be in an unexpected state where _waitInProgress being not null, which may affect other Process.WaitForExit calls on the same process.

danmoseley · 2023-05-06T14:04:49Z

Either of you interested in offering a PR?

skyoxZ · 2023-05-06T15:39:23Z

@danmoseley I'd like to have a try. Could you please assign it to me?

danmoseley · 2023-05-06T18:41:32Z

Done!

dotnet-issue-labeler bot added the area-System.Diagnostics.Process label May 3, 2023

ghost added the untriaged New issue has not been triaged by the area owner label May 3, 2023

danmoseley assigned skyoxZ May 6, 2023

skyoxZ mentioned this issue May 7, 2023

Fix WaitForExitAsync could return a cancelled task #85882

Closed

ghost added the in-pr There is an active PR which will close this issue when it is merged label May 7, 2023

adamsitnik removed the untriaged New issue has not been triaged by the area owner label May 11, 2023

adamsitnik added this to the 8.0.0 milestone May 11, 2023

ghost removed the in-pr There is an active PR which will close this issue when it is merged label Jun 6, 2023

stephentoub mentioned this issue Jun 6, 2023

Fix a couple of issues related to Process.WaitForExit on Unix #87174

Merged

ghost added the in-pr There is an active PR which will close this issue when it is merged label Jun 6, 2023

jozkee closed this as completed in #87174 Jun 20, 2023

ghost removed the in-pr There is an active PR which will close this issue when it is merged label Jun 20, 2023

ghost locked as resolved and limited conversation to collaborators Jul 21, 2023

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Process.WaitForExit(Int32) sometimes throws AggregateException on macOS #85717

Process.WaitForExit(Int32) sometimes throws AggregateException on macOS #85717

Metalnem commented May 3, 2023

ghost commented May 3, 2023

Description

Reproduction Steps

Expected behavior

Actual behavior

Regression?

Known Workarounds

Configuration

Other information

skyoxZ commented May 6, 2023

danmoseley commented May 6, 2023

skyoxZ commented May 6, 2023

danmoseley commented May 6, 2023

Process.WaitForExit(Int32) sometimes throws AggregateException on macOS #85717

Process.WaitForExit(Int32) sometimes throws AggregateException on macOS #85717

Comments

Metalnem commented May 3, 2023

Description

Reproduction Steps

Expected behavior

Actual behavior

Regression?

Known Workarounds

Configuration

Other information

ghost commented May 3, 2023

Description

Reproduction Steps

Expected behavior

Actual behavior

Regression?

Known Workarounds

Configuration

Other information

skyoxZ commented May 6, 2023

danmoseley commented May 6, 2023

skyoxZ commented May 6, 2023

danmoseley commented May 6, 2023