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fix awaitCompletion method functionality #9381

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fix awaitCompletion method functionality #9381

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6 changes: 2 additions & 4 deletions commandsv3/src/main/java/org/wpilib/command3/Coroutine.java
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Original file line number Diff line number Diff line change
Expand Up @@ -202,10 +202,8 @@ public boolean partialSuccess() {
* <p>This method does nothing if no commands were successfully forked.
*/
public void awaitCompletion() {
for (Command command : m_forkedCommands) {
if (m_scheduler.isRunning(command)) {
Coroutine.this.yield();
}
while (m_forkedCommands.stream().anyMatch(m_scheduler::isRunning)) {

@chatgpt-codex-connector chatgpt-codex-connector Bot Sep 4, 2026

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P2 Badge Stop tracking a fork entry after its original run ends

When one forked command completes while another remains active, this loop keeps the completed command in m_forkedCommands; if that same Command instance is subsequently scheduled again by a trigger, default binding, or direct scheduler call, isRunning() treats the new execution as part of the old fork. The parent then waits for this unrelated run and can hang indefinitely if it is persistent, contrary to the documented promise that completed forked commands are not rescheduled or awaited again. Track the original scheduling lifecycle, or permanently retire each entry once its forked execution ends.

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@hadley31 hadley31 Sep 7, 2026

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@SamCarlberg curious your thoughts on this—if this is a real concern, we could possibly track the ids of the originally scheduled commands:

    public void awaitCompletion() {
      Set<Integer> ids = m_forkedCommands.stream().map(Scheduler.getDefault()::runId).filter(x -> x > 0).collect(Collectors.toSet());
      Predicate<Command> isCommandStillRunning = command -> ids.contains(Scheduler.getDefault().runId(command));
      while (m_forkedCommands.stream().anyMatch(isCommandStillRunning)) {
        Coroutine.this.yield();
      }
    }

But I could also be overthinking this

Coroutine.this.yield();
}
}

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