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fix: prevent Aspire manifest generation hang from MSBuild node reuse #9347

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fix: prevent Aspire manifest generation hang from MSBuild node reuse #9347

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367eee1
fix: prevent Aspire manifest generation hang from MSBuild node reuse
vhvb1989 Jul 29, 2026
67d6503
fix: add MSBUILDDISABLENODEREUSE to cspell dictionary
vhvb1989 Jul 29, 2026
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3 changes: 3 additions & 0 deletions cli/azd/.vscode/cspell.yaml
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Original file line number Diff line number Diff line change
Expand Up @@ -181,6 +181,9 @@ overrides:
- compatResult
- compatCopy
- Incompat
- filename: pkg/tools/dotnet/dotnet.go
words:
- MSBUILDDISABLENODEREUSE
- filename: pkg/output/pretty_table.go
words:
- runewidth
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17 changes: 12 additions & 5 deletions cli/azd/pkg/tools/dotnet/dotnet.go
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Expand Up @@ -202,17 +202,24 @@ func (cli *Cli) PublishAppHostManifest(

runArgs = runArgs.WithCwd(filepath.Dir(hostProject))

// Disable MSBuild node reuse for this invocation. `dotnet run --publisher manifest` builds the AppHost via
// MSBuild, which by default spawns persistent worker nodes (nodeReuse:true) that survive after `dotnet run`
// exits. Those worker nodes inherit the stdout/stderr pipe that azd's command runner reads from, so the pipe
// never reaches EOF and cmd.Wait() blocks forever even though the manifest was already produced. This is the
// os/exec deadlock described in https://github.com/golang/go/issues/23019 and reported in azd issue #9295
// (hangs with 0% CPU on large solutions where many worker nodes are spawned). Disabling node reuse makes the
// worker nodes terminate when the build completes, closing the inherited pipe.
envArgs := []string{

@jongio jongio Jul 31, 2026

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Scoping the env var to this one call means Restore, Build, Publish, BuildContainerLocal, and PublishContainer still run MSBuild with node reuse on, through the same commandRunner.Run path that captures stdout/stderr into bytes.Buffer. The deadlock exposure there looks identical to what's described for manifest generation.

The PR description frames leaving them alone as a performance decision, but it doesn't cover the hang risk. On the same 54-project solution from #9295, what keeps dotnet publish during azd deploy from wedging the same way? If the answer is that it can and it just hasn't been reported yet, that's worth noting on the issue so it isn't rediscovered later.

"MSBUILDDISABLENODEREUSE=1",
}

// AppHost may conditionalize their infrastructure based on the environment, so we need to pass the environment when we
// are `dotnet run`ing the app host project to produce its manifest.
var envArgs []string

if dotnetEnv != "" {
envArgs = append(envArgs, fmt.Sprintf("DOTNET_ENVIRONMENT=%s", dotnetEnv))
}

if envArgs != nil {
runArgs = runArgs.WithEnv(envArgs)
}
runArgs = runArgs.WithEnv(envArgs)

_, err := cli.commandRunner.Run(ctx, runArgs)
if err != nil {
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3 changes: 3 additions & 0 deletions cli/azd/pkg/tools/dotnet/dotnet_commands_test.go
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Expand Up @@ -332,6 +332,8 @@ func Test_Cli_PublishAppHostManifest(t *testing.T) {
require.Contains(t, captured.Args, "--output-path")
require.Contains(t, captured.Args, "out.json")
require.Contains(t, captured.Env, "DOTNET_ENVIRONMENT=Development")
// Node reuse must be disabled to avoid the os/exec pipe-inheritance hang (issue #9295).
require.Contains(t, captured.Env, "MSBUILDDISABLENODEREUSE=1")
})

t.Run("single file apphost", func(t *testing.T) {
Expand All @@ -349,6 +351,7 @@ func Test_Cli_PublishAppHostManifest(t *testing.T) {
require.Equal(t, filepath.Dir(hostProject), captured.Cwd)
require.Equal(t, "apphost.cs", captured.Args[1])
require.NotContains(t, captured.Args, "--project")
require.Contains(t, captured.Env, "MSBUILDDISABLENODEREUSE=1")
})

t.Run("run error", func(t *testing.T) {
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