Guard get_state liveness probe during pooled H2/H3 checkout (#914) - #915
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Reusing a pooled HTTP/2 or HTTP/3 connection probes it with hackney_conn:get_state/1, a bare gen_statem:call. If the connection is terminating at that instant (idle teardown, GOAWAY, keepalive close) the call exits, and the surrounding case only handled return values, so the exit crashed the caller of hackney:connect/4 instead of falling through to a fresh connection. Wrap both checkout probes in try/catch exit, mirroring the existing race handling in maybe_register_h2 and maybe_upgrade_ssl. A terminating connection is now treated as unusable and the checkout opens a fresh one.
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benoitc added a commit
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Aug 11, 2026
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Fixes#914.
Reusing a pooled HTTP/2 or HTTP/3 connection probes it with
hackney_conn:get_state/1, a baregen_statem:call. If the pooled connection is terminating at that instant (idle teardown, GOAWAY, keepalive close) the call exits. The surroundingcaseonly handled return values, so the exit propagated and crashed the caller ofhackney:connect/4({noproc,{gen_statem,call,[Pid,get_state]}}) instead of falling through to a fresh connection.The same file already guards the sibling probes for this exact race in
maybe_register_h2andmaybe_upgrade_ssl; the twoget_statecheckout probes were missed.Change
Wrap both checkout probes in
try ... catch exit:_ -> {error, terminated} end(H2 site inconnect_pool/4, H3 site intry_h3_connection/5). A terminating connection is treated as unusable and checkout falls through to the existing unregister + new-connection path. Onlyexitis caught;error/throwwould be a genuine bug and still propagate.Tests
New
hackney_connect_race_testswith ahackney_race_poolhandler that hands out an already-terminated pid on H2/H3 checkout. H2 assertshackney:connect/4returns{error, _}; H3 asserts theget_stateprobe exit does not escape. Reverting the guard makes both fail with the{noproc,...get_state...}exit. Full suite (1054 tests) passes.