EC
subprocess.TimeoutExpired
PythonERRORNotableRuntime ErrorHIGH confidence

Subprocess timed out

Production Risk

Always kill subprocess on timeout and collect output to avoid orphan processes.

What this means

Raised by subprocess.run() or subprocess.communicate() when the child process does not finish within the specified timeout.

Why it happens
  1. 1External command takes longer than expected
  2. 2Command hangs waiting for input
  3. 3Network operation in subprocess stalls
How to reproduce

Running a slow command with a timeout.

trigger — this will error
trigger — this will error
import subprocess
subprocess.run(['sleep', '30'], timeout=5)

expected output

subprocess.TimeoutExpired: Command '['sleep', '30']' timed out after 5 seconds

Fix

Kill the process after timeout

WHEN Handling TimeoutExpired

Kill the process after timeout
import subprocess

proc = subprocess.Popen(['slow_command'])
try:
    stdout, stderr = proc.communicate(timeout=30)
except subprocess.TimeoutExpired:
    proc.kill()
    stdout, stderr = proc.communicate()  # collect remaining output
    print("Command timed out and was killed")

Why this works

proc.kill() sends SIGKILL; calling communicate() after ensures the process is fully reaped.

Code examples
Triggerpython
import subprocess
subprocess.run(["sleep", "30"], timeout=5)  # TimeoutExpired after 5 seconds
Handle with killpython
import subprocess
proc = subprocess.Popen(["slow_cmd"])
try:
    out, _ = proc.communicate(timeout=30)
except subprocess.TimeoutExpired:
    proc.kill()
    proc.communicate()
Avoid with reasonable timeoutpython
import subprocess
result = subprocess.run(
    cmd,
    timeout=60,
    capture_output=True
)
# Always set a timeout — never leave unbounded
What not to do

✕ Ignore TimeoutExpired and let the process continue running

The process becomes a zombie/orphan consuming resources; always kill it on timeout.

Sources
Official documentation ↗

Python Docs — subprocess module

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