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Problem

You want to react to job completions as they happen, rather than polling or blocking. This is useful for long-running batch jobs or when you need to trigger actions based on results.

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Solution

Use filesystem watching tools like fswatch (macOS/Linux) or inotifywait (Linux) to monitor the workspace output directory. When a job completes, trigger processing immediately.

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Example

Monitor completions with fswatch: 
# Terminal 1: Watch for results
fswatch -0 ./workspace/output | while read -d '' path; do
  [[ "$path" == */result.txt ]] && cat "$path"
done

# Terminal 2: Submit jobs
wrk ./workspace "Question 1"
wrk ./workspace "Question 2"

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Batch Processing with Events

Submit many jobs and collect results as they complete: 
# Submit 100 jobs in seconds
for img in photos/*.jpg; do
  wrk ./workspace "Caption this image" --image "$img" >> jobs.txt
done

# Check progress
ls ./workspace/output/ | wc -l

# Collect all results
for job in $(cat jobs.txt); do
  echo "=== $job ==="
  flw ./workspace $job
done

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Advanced Event Handling

Trigger subsequent jobs: 
fswatch -0 ./workspace/output | while read -d '' path; do
  if [[ "$path" == */result.txt ]]; then
    result=$(cat "$path")
    # Submit follow-up job based on result
    if echo "$result" | grep -q "needs_review"; then
      wrk ./workspace "Review this: $result"
    fi
  fi
done
Log completions: 
fswatch -0 ./workspace/output | while read -d '' path; do
  [[ "$path" == */result.txt ]] && {
    echo "[$(date)] Job completed: $path" | tee -a completion.log
  }
done
Parallel monitoring: 
# Watch multiple workspaces
fswatch -0 ./ws-vision/output ./ws-code/output ./ws-fast/output | \
while read -d '' path; do
  workspace=$(echo "$path" | cut -d/ -f2)
  echo "[$workspace] Completed: $(cat "$path")"
done

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How It Works

  • fswatch -0 watches directories for changes (null-terminated output)
  • read -d '' reads null-terminated paths
  • Pattern matching identifies completed jobs (*/result.txt)
  • Actions trigger immediately when files are written

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Linux Alternative

Using inotifywait on Linux: 
inotifywait -m -e close_write --format '%w%f' ./workspace/output | \
while read path; do
  [[ "$path" == */result.txt ]] && cat "$path"
done

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Use Cases

  • Real-time processing: React to results immediately
  • Pipeline triggers: Start next stage when previous completes
  • Monitoring dashboards: Display results as they arrive
  • Progress tracking: Update UI or logs in real-time
  • Conditional workflows: Different actions based on result content

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