{ "number": 35932, "repo": "bitcoin/bitcoin", "url": "https://github.com/bitcoin/bitcoin/pull/35932", "title": "ipc: make ipc::disconnectIncoming wait for in-progress calls to complete", "author": "ryanofsky", "author_association": "MEMBER", "created_at": "2026-08-07T14:13:39Z", "updated_at": "2026-09-10T08:38:15Z", "age_days": 41, "draft": true, "labels": [ "IPC", "CI failed" ], "milestone": null, "base": "master", "head_sha": "451f5455d6a139f7df2bbcd3f27b5143e9fbc65d", "head_ref": "pr/diswait", "head_repo": "ryanofsky/bitcoin", "head_history": [ { "t": "2026-08-12T20:17:52Z", "sha": "451f5455d6a139f7df2bbcd3f27b5143e9fbc65d" } ], "additions": 339, "deletions": 21, "changed_files": 5, "commit_count": 5, "size_bucket": "M", "mergeable_state": "unstable", "bot": { "drahtbot": { "present": true, "reviews": {}, "conflicts": [ { "number": 36097, "title": "mining: replace interrupt methods with cancellation arguments", "author": "xyzconstant" }, { "number": 32387, "title": "ipc: add windows support", "author": "ryanofsky" }, { "number": 29409, "title": "multiprocess: Add capnp wrapper for Chain interface", "author": "ryanofsky" }, { "number": 19461, "title": "multiprocess: Add bitcoin-gui -ipcconnect option", "author": "ryanofsky" }, { "number": 19460, "title": "multiprocess: Add bitcoin-wallet -ipcconnect option", "author": "ryanofsky" }, { "number": 10102, "title": "Multiprocess bitcoin", "author": "ryanofsky" } ] } }, "acks_parsed": {}, "acks_tally": { "ack": 0, "stale_ack": 0, "concept_ack": 0, "approach_ack": 0, "nack": 0, "concept_nack": 0, "approach_nack": 0 }, "reviews": { "approved": 0, "changes_requested": 0, "distinct_reviewers": [] }, "signals": { "needs_rebase": false, "ci_failed": true, "mergeable_state": "unstable", "last_author_activity": "2026-08-12T20:19:43Z", "last_reviewer_activity": null, "last_reviewer": null, "author_silent_days": 35, "waiting_on_author_days": 0, "days_since_update": 7 }, "refs": { "mentioned": [], "depends_on": [], "fixes": [], "linked_issues": [], "references": [], "conflicts": [ 36097, 32387, 29409, 19461, 19460, 10102 ] }, "stack": { "shares_commits_with": [], "based_on": [], "base_for": [] }, "review_paths": [], "body": "This fixes an antithesis bug reported https://github.com/bitcoin/bitcoin/issues/35845 and similar bug reported in https://github.com/bitcoin/bitcoin/issues/33387 where if asynchronous IPC mining calls are made when the node is shutting down it's possible for `assert(m_node.chainman)` to trigger. This happens because the `Ipc::disconnectIncoming` method does not wait for asynchronous calls to complete after it disconnects IPC clients, so they may continue to run as the node is shutting down.\n\nThis PR changes `disconnectIncoming` to wait for asynchronous calls to complete to avoid this issue. It's a draft because it depends on libmultiprocess changes, but should otherwise be ready to review.\n\n**This is based on https://github.com/bitcoin-core/libmultiprocess/pull/335.**", "commits": [ { "sha": "4a04be58d0ba036ecf27e8214b29f411f544d369", "date": "2026-07-31T19:19:30Z", "message": "ipc: add Connection::disconnect() separating teardown from destruction\n\nSplit connection teardown out of ~Connection into an idempotent disconnect()\nmethod, with the destructor delegating to it. This is a behavior-neutral\nrefactor: the same steps run in the same order on destruction.\n\nHaving a separate disconnect() method allows severing a connection while\nkeeping the Connection object alive, which the next commits use to let\nshutdown code wait for in-flight server call bodies to finish after a\ndisconnect (bitcoin/bitcoin#35845). Two details are new:\n\n- disconnect() cancels the m_on_disconnect handlers before severing the\n connection. Previously they were implicitly canceled when the TaskSet\n member was destroyed. When disconnect() is called separately from\n destruction, this is required for correctness: severing the stream\n completes m_network.onDisconnect(), and the registered handlers (_Serve,\n ConnectStream) destroy the Connection object out from under the caller.\n\n- disconnect() explicitly releases m_thread_pool and m_thread_map so worker\n thread teardown happens at disconnect time whether or not the object is\n destroyed right away. Previously this happened implicitly during member\n destruction.\n\nCo-Authored-By: Claude Fable 5 " }, { "sha": "cf7261b35448aa4d871c40c9d6a40043259c11ea", "date": "2026-07-31T19:21:48Z", "message": "ipc: add Connection::waitDrained() to wait for in-flight server calls\n\nAdd a per-connection ServerObjectTracker counting live ProxyServer objects,\nincremented in the ProxyServerBase constructor and decremented in its\ndestructor, with Connection::waitDrained() blocking until the count reaches\nzero and Connection::pendingServerObjects() exposing it for logging.\n\nDisconnecting a connection cancels the KJ promise of an in-flight call, but a\nC++ server method body already dispatched to a worker thread runs to\ncompletion. Counting live server objects turns Cap'n Proto's object lifetime\nrules into a usable quiescence signal: a ProxyServer object is not destroyed\nuntil its outstanding calls finish (the target capability is kept alive for\nthe duration of a call and pinned by post()/PassField via thisCap()), so\nafter disconnect() the count drains to zero exactly when no server call body\nis still executing. Waiting for that lets shutdown code avoid freeing\napplication state that a still-running call body dereferences\n(bitcoin/bitcoin#35845).\n\nThe tracker is held via shared_ptr by the Connection and by every\nProxyServer object because objects kept alive by in-flight calls can outlive\nthe Connection on some teardown paths (see ~ProxyServerBase), and their\ndestructors must decrement state that is still valid. It must be declared\nbefore m_rpc_system, whose construction creates the bootstrap server object\nthat registers itself with the tracker.\n\nCo-Authored-By: Claude Fable 5 " }, { "sha": "a28447e75f33ce1899b20c65c0fe8d097061ccd1", "date": "2026-07-31T19:40:26Z", "message": "test: cover draining in-flight server call after disconnect\n\nAdd a deterministic mptest regression test for bitcoin/bitcoin#35845: hold a\nserver method body in flight on a worker thread, call\nConnection::disconnect(), and assert that Connection::waitDrained() blocks\nuntil the body finishes and its server object is destroyed. Also covers\ndestroying an already-disconnected connection (~Connection noticing\ndisconnect() has run).\n\nCo-Authored-By: Claude Fable 5 " }, { "sha": "a882e0d63f38876a82bc8f187ae84ccfa85bcfbc", "date": "2026-08-10T19:37:25Z", "message": "Add EventLoop::incoming_connections() that returns std::views::all of the\nm_incoming_connections list. Currently the list holds Connection by value\nso the view yields Connection&. When keepconn+notrack later changes the\nlist to list>, the accessor will be updated to\nreturn a transform view, so Bitcoin Core code that iterates via this\naccessor compiles unchanged across that type change.\n\nCo-Authored-By: Claude Sonnet 4.6 " }, { "sha": "451f5455d6a139f7df2bbcd3f27b5143e9fbc65d", "date": "2026-08-10T19:37:25Z", "message": "ipc: drain in-flight server calls before shutdown frees node state\n\nFix bitcoin/bitcoin#35845, an assertion failure in MinerImpl::chainman()\nduring shutdown of an IPC-mining node.\n\nShutdown() calls disconnectIncoming() before node.chainman.reset().\nDisconnecting cancels the KJ promise of an in-flight IPC server call, but a\nC++ server method body already dispatched to a libmultiprocess worker thread\nis not interrupted and runs to completion. A still-running body (an in-flight\nMining.checkBlock) could then dereference m_node.chainman after\nchainman.reset() nulled it, aborting on Assert(m_node.chainman).\n\nMake disconnectIncoming() disconnect the non-parent incoming connections,\nwait off the event loop thread for their in-flight server call bodies to\nfinish (Connection::waitDrained), and only then destroy them and return, so\nShutdown() frees node state only once no server code is running. Log when\nthe wait actually blocks so a shutdown hang here is diagnosable.\n\nNo wait is needed for calls parked in waitTipChanged()/waitNext():\nInterrupt() runs before Shutdown() and notifies m_tip_block_cv after setting\nthe shutdown signal, so those return before disconnectIncoming() runs.\n\nIntentional limitations, to keep the fix narrow: m_impl destructors\nscheduled on the async cleanup thread are not waited for, the kept-open\nparent connection is not drained, and new incoming connections can still be\naccepted during shutdown (preventing that needs a listener API, proposed in\nbitcoin-core/libmultiprocess#269).\n\nCo-Authored-By: Claude Fable 5 " } ], "timeline": [ { "t": "2026-08-12T20:17:52Z", "kind": "force_push", "who": "ryanofsky", "commit": "451f5455d6a139f7df2bbcd3f27b5143e9fbc65d" }, { "t": "2026-08-12T20:19:43Z", "kind": "comment", "who": "ryanofsky", "assoc": "MEMBER", "text": "Updated b0c970e305fde426f4aacc8f8d9ea55ea6e8e210 -> 451f5455d6a139f7df2bbcd3f27b5143e9fbc65d ([`pr/diswait.4`](https://github.com/ryanofsky/bitcoin/commits/pr/diswait.4) -> [`pr/diswait.5`](https://github.com/ryanofsky/bitcoin/commits/pr/diswait.5), [compare](https://github.com/ryanofsky/bitcoin/compare/pr/diswait.4..pr/diswait.5)) using `incoming_connections()` accessor for compatibility with https://github.com/bitcoin-core/libmultiprocess/pull/336" } ], "labels_log": [ { "t": "2026-08-07T14:13:42Z", "action": "labeled", "label": "IPC", "who": "DrahtBot" }, { "t": "2026-08-07T16:14:53Z", "action": "labeled", "label": "CI failed", "who": "DrahtBot" } ], "state_log": [], "text_chars": 6627, "text_tokens_estimate": 1656, "changed_paths": [ "src/ipc/capnp/protocol.cpp", "src/ipc/libmultiprocess/include/mp/proxy-io.h", "src/ipc/libmultiprocess/include/mp/proxy.h", "src/ipc/libmultiprocess/src/mp/proxy.cpp", "src/ipc/libmultiprocess/test/mp/test/test.cpp" ], "files": [ { "path": "src/ipc/capnp/protocol.cpp", "add": 50, "del": 2 }, { "path": "src/ipc/libmultiprocess/include/mp/proxy-io.h", "add": 151, "del": 14 }, { "path": "src/ipc/libmultiprocess/include/mp/proxy.h", "add": 7, "del": 0 }, { "path": "src/ipc/libmultiprocess/src/mp/proxy.cpp", "add": 60, "del": 5 }, { "path": "src/ipc/libmultiprocess/test/mp/test/test.cpp", "add": 71, "del": 0 } ], "test_lines": 0, "git": { "head": "451f5455d6a139f7df2bbcd3f27b5143e9fbc65d", "head_matches_backup": true, "base": "67efced1fc83a0b7215cc1513e7c4754fee0f12f", "commits": [ { "sha": "4a04be58d0", "subject": "ipc: add Connection::disconnect() separating teardown from destruction", "files": 2, "add": 85, "del": 18 }, { "sha": "cf7261b354", "subject": "ipc: add Connection::waitDrained() to wait for in-flight server calls", "files": 3, "add": 129, "del": 1 }, { "sha": "a28447e75f", "subject": "test: cover draining in-flight server call after disconnect", "files": 1, "add": 71, "del": 0 }, { "sha": "a882e0d63f", "subject": "Add EventLoop::incoming_connections() that returns std::views::all of the m_incoming_connections list. Currently the list holds Connection by value so the view yields Connection&. When keepconn+notrack later changes the list to list>, the accessor will be updated to return a transform view, so Bitcoin Core code that iterates via this accessor compiles unchanged across that type change.", "files": 1, "add": 4, "del": 0 }, { "sha": "451f5455d6", "subject": "ipc: drain in-flight server calls before shutdown frees node state", "files": 1, "add": 50, "del": 2 } ], "patch_truncated": false }, "input_hash": "8b7c8ededcccb1ae", "extracted_at": "2026-09-17T16:15:31+00:00" }