[route]

Not for merging. On main the JRuby job failed once in spec/client_spec.rb:105 ("times out a command waiting to be sent and keeps the connection"): the 16MB command got DeadBrowserError about 5s after it was sent, although Chrome was resumed after ~0.7s. It doesn't reproduce locally on macOS or in a 2-CPU Linux container.

This runs the JRuby job 10 times in parallel, each time the full suite and then the example alone 10 times, with FERRUM_STALL_DEBUG=1 loading spec/support/stall_debug.rb. For a frame over 1MB it logs:

• every chunk that takes over 0.2s, and while one is stuck, every 0.5s: ss -tmioe for the socket (send/receive queues, window, persist timer), /proc/loadavg and Chrome's process state;
• STOP, CONT and what each command returned;
• when the watchdog fires, the same snapshot plus every thread's backtrace.

The log is printed in the "Stall log" step and uploaded as stall-debug-N.