tor fails to kill its pluggable transports when it's done using them

Seems like Tor does not successfully kill obfs4proxy (or any other transport) when it's no longer used. It's unclear why. Maybe obfs4proxy never receives the SIGTERM, or never notices that the stdin is closed?

Experiment:

Startup Tor Browser using default obfs4 bridges.
Check that obfs4proxy process has spawned (ps -fax | grep obfs)
Reconfigure Tor Browser to not use bridges at all.
Check that obfs4proxy process is still there...

Edited Aug 04, 2020 by Roger Dingledine

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