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Cancellation can get stuck when a child process inherits stdout/stderr #153

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Cancellation can get stuck when a child process inherits stdout/stderr#153

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@borland
borland
opened on Jul 8, 2026

Add failing repro for grandchild-pipe hang on sync Execute adds a failing test which demonstrates a problem:

  • Use shellfish to launch a process (e.g. powershell)
  • That process then launches a child process (e.g. a second powershell), which inherits the STDOUT/STDERR pipes
  • The first process exits, but the child process keeps running, and holds the pipes open
  • Cancel the cancellation token.

On the synchronous path, this waits indefinitely for the child process. If the child process is hung or otherwise runs for a long time, the Cancellation doesn't work.

The async path appears to be fine, possibly because it does not wait for the process to cancel.

This is not causing problems for any current uses of Shellfish that we are aware of; we found it in a different piece of code and reporting it against Shellfish for completeness. It would be nice to fix, ideally Shellfish is the best/de-facto tool for running processes for Octopus.

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var __re = new RegExp('^' + "github\\.com" + '
Cancellation can get stuck when a child process inherits stdout/stderr · Issue #153 · OctopusDeploy/Shellfish · GitHub
      Skip to content
      Cancellation can get stuck when a child process inherits stdout/stderr #153
      Open
      Open
      Cancellation can get stuck when a child process inherits stdout/stderr#153
      Description
      @borland
      borland
      opened on Jul 8, 2026
      Add failing repro for grandchild-pipe hang on sync Execute adds a failing test which demonstrates a problem:
      • Use shellfish to launch a process (e.g. powershell)
      • That process then launches a child process (e.g. a second powershell), which inherits the STDOUT/STDERR pipes
      • The first process exits, but the child process keeps running, and holds the pipes open
      • Cancel the cancellation token.
      On the synchronous path, this waits indefinitely for the child process. If the child process is hung or otherwise runs for a long time, the Cancellation doesn't work.
      The async path appears to be fine, possibly because it does not wait for the process to cancel.
      This is not causing problems for any current uses of Shellfish that we are aware of; we found it in a different piece of code and reporting it against Shellfish for completeness. It would be nice to fix, ideally Shellfish is the best/de-facto tool for running processes for Octopus.
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, 'i');
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try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Cancellation can get stuck when a child process inherits stdout/stderr · Issue #153 · OctopusDeploy/Shellfish · GitHub
          Skip to content
          Cancellation can get stuck when a child process inherits stdout/stderr #153
          Open
          Open
          Cancellation can get stuck when a child process inherits stdout/stderr#153
          Description
          @borland
          borland
          opened on Jul 8, 2026
          Add failing repro for grandchild-pipe hang on sync Execute adds a failing test which demonstrates a problem:
          • Use shellfish to launch a process (e.g. powershell)
          • That process then launches a child process (e.g. a second powershell), which inherits the STDOUT/STDERR pipes
          • The first process exits, but the child process keeps running, and holds the pipes open
          • Cancel the cancellation token.
          On the synchronous path, this waits indefinitely for the child process. If the child process is hung or otherwise runs for a long time, the Cancellation doesn't work.
          The async path appears to be fine, possibly because it does not wait for the process to cancel.
          This is not causing problems for any current uses of Shellfish that we are aware of; we found it in a different piece of code and reporting it against Shellfish for completeness. It would be nice to fix, ideally Shellfish is the best/de-facto tool for running processes for Octopus.
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, 'i');
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(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Cancellation can get stuck when a child process inherits stdout/stderr · Issue #153 · OctopusDeploy/Shellfish · GitHub
              Skip to content
              Cancellation can get stuck when a child process inherits stdout/stderr #153
              Open
              Open
              Cancellation can get stuck when a child process inherits stdout/stderr#153
              Description
              @borland
              borland
              opened on Jul 8, 2026
              Add failing repro for grandchild-pipe hang on sync Execute adds a failing test which demonstrates a problem:
              • Use shellfish to launch a process (e.g. powershell)
              • That process then launches a child process (e.g. a second powershell), which inherits the STDOUT/STDERR pipes
              • The first process exits, but the child process keeps running, and holds the pipes open
              • Cancel the cancellation token.
              On the synchronous path, this waits indefinitely for the child process. If the child process is hung or otherwise runs for a long time, the Cancellation doesn't work.
              The async path appears to be fine, possibly because it does not wait for the process to cancel.
              This is not causing problems for any current uses of Shellfish that we are aware of; we found it in a different piece of code and reporting it against Shellfish for completeness. It would be nice to fix, ideally Shellfish is the best/de-facto tool for running processes for Octopus.
              Metadata
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, 'i');
if (__m === '*' || __re.test(location.href)) {
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observer.observe(document.body, { childList: true, subtree: true });
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} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
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(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '
Cancellation can get stuck when a child process inherits stdout/stderr · Issue #153 · OctopusDeploy/Shellfish · GitHub
                  Skip to content
                  Cancellation can get stuck when a child process inherits stdout/stderr #153
                  Open
                  Open
                  Cancellation can get stuck when a child process inherits stdout/stderr#153
                  Description
                  @borland
                  borland
                  opened on Jul 8, 2026
                  Add failing repro for grandchild-pipe hang on sync Execute adds a failing test which demonstrates a problem:
                  • Use shellfish to launch a process (e.g. powershell)
                  • That process then launches a child process (e.g. a second powershell), which inherits the STDOUT/STDERR pipes
                  • The first process exits, but the child process keeps running, and holds the pipes open
                  • Cancel the cancellation token.
                  On the synchronous path, this waits indefinitely for the child process. If the child process is hung or otherwise runs for a long time, the Cancellation doesn't work.
                  The async path appears to be fine, possibly because it does not wait for the process to cancel.
                  This is not causing problems for any current uses of Shellfish that we are aware of; we found it in a different piece of code and reporting it against Shellfish for completeness. It would be nice to fix, ideally Shellfish is the best/de-facto tool for running processes for Octopus.
                  Metadata
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                      No branches or pull requests
                      Issue actions
                      
, 'i');
if (__m === '*' || __re.test(location.href)) {
// Auto-enable theater mode on YouTube
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function tryTheater() {
var btn = document.querySelector('button[aria-label="Theater mode"], ytd-player #player button[title="Theater mode"]');
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(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Cancellation can get stuck when a child process inherits stdout/stderr · Issue #153 · OctopusDeploy/Shellfish · GitHub
                      Skip to content
                      Cancellation can get stuck when a child process inherits stdout/stderr #153
                      Open
                      Open
                      Cancellation can get stuck when a child process inherits stdout/stderr#153
                      Description
                      @borland
                      borland
                      opened on Jul 8, 2026
                      Add failing repro for grandchild-pipe hang on sync Execute adds a failing test which demonstrates a problem:
                      • Use shellfish to launch a process (e.g. powershell)
                      • That process then launches a child process (e.g. a second powershell), which inherits the STDOUT/STDERR pipes
                      • The first process exits, but the child process keeps running, and holds the pipes open
                      • Cancel the cancellation token.
                      On the synchronous path, this waits indefinitely for the child process. If the child process is hung or otherwise runs for a long time, the Cancellation doesn't work.
                      The async path appears to be fine, possibly because it does not wait for the process to cancel.
                      This is not causing problems for any current uses of Shellfish that we are aware of; we found it in a different piece of code and reporting it against Shellfish for completeness. It would be nice to fix, ideally Shellfish is the best/de-facto tool for running processes for Octopus.
                      Metadata
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                          No branches or pull requests
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, 'i');
if (__m === '*' || __re.test(location.href)) {
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function unstick() {
document.querySelectorAll('header, nav, [role="banner"], .header, .navbar, .sticky, .fixed-top, [style*="position: fixed"], [style*="position:sticky"]').forEach(function(el) {
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var observer = new MutationObserver(unstick);
observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });
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} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
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(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Cancellation can get stuck when a child process inherits stdout/stderr · Issue #153 · OctopusDeploy/Shellfish · GitHub
                          Skip to content
                          Cancellation can get stuck when a child process inherits stdout/stderr #153
                          Open
                          Open
                          Cancellation can get stuck when a child process inherits stdout/stderr#153
                          Description
                          @borland
                          borland
                          opened on Jul 8, 2026
                          Add failing repro for grandchild-pipe hang on sync Execute adds a failing test which demonstrates a problem:
                          • Use shellfish to launch a process (e.g. powershell)
                          • That process then launches a child process (e.g. a second powershell), which inherits the STDOUT/STDERR pipes
                          • The first process exits, but the child process keeps running, and holds the pipes open
                          • Cancel the cancellation token.
                          On the synchronous path, this waits indefinitely for the child process. If the child process is hung or otherwise runs for a long time, the Cancellation doesn't work.
                          The async path appears to be fine, possibly because it does not wait for the process to cancel.
                          This is not causing problems for any current uses of Shellfish that we are aware of; we found it in a different piece of code and reporting it against Shellfish for completeness. It would be nice to fix, ideally Shellfish is the best/de-facto tool for running processes for Octopus.
                          Metadata
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, 'i');
if (__m === '*' || __re.test(location.href)) {
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if (!enabled) return;
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style = document.createElement('style');
style.id = 'universal-dark-mode-style';
document.head.appendChild(style);
}
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filter: invert(1) hue-rotate(180deg) !important;
background: #1a1a2e !important;
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console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');
})();
}
} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
})();
})();
Cancellation can get stuck when a child process inherits stdout/stderr · Issue #153 · OctopusDeploy/Shellfish · GitHub
                              Skip to content
                              Cancellation can get stuck when a child process inherits stdout/stderr #153
                              Open
                              Open
                              Cancellation can get stuck when a child process inherits stdout/stderr#153
                              Description
                              @borland
                              borland
                              opened on Jul 8, 2026
                              Add failing repro for grandchild-pipe hang on sync Execute adds a failing test which demonstrates a problem:
                              • Use shellfish to launch a process (e.g. powershell)
                              • That process then launches a child process (e.g. a second powershell), which inherits the STDOUT/STDERR pipes
                              • The first process exits, but the child process keeps running, and holds the pipes open
                              • Cancel the cancellation token.
                              On the synchronous path, this waits indefinitely for the child process. If the child process is hung or otherwise runs for a long time, the Cancellation doesn't work.
                              The async path appears to be fine, possibly because it does not wait for the process to cancel.
                              This is not causing problems for any current uses of Shellfish that we are aware of; we found it in a different piece of code and reporting it against Shellfish for completeness. It would be nice to fix, ideally Shellfish is the best/de-facto tool for running processes for Octopus.
                              Metadata
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