From 3bdea167eb01491a4898e977d308508374e97bfa Mon Sep 17 00:00:00 2001 From: Andres Freund Date: Sun, 18 Jun 2017 18:48:22 -0700 Subject: [PATCH] Fix leaking of small spilled subtransactions during logical decoding. MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit When, during logical decoding, a transaction gets too big, it's contents get spilled to disk. Not just the top-transaction gets spilled, but *also* all of its subtransactions, even if they're not that large themselves. Unfortunately we didn't clean up such small spilled subtransactions from disk. Fix that, by keeping better track of whether a transaction has been spilled to disk. Author: Andres Freund Reported-By: Dmitriy Sarafannikov, Fabrízio de Royes Mello Discussion: https://postgr.es/m/1457621358.355011041@f382.i.mail.ru https://postgr.es/m/CAFcNs+qNMhNYii4nxpO6gqsndiyxNDYV0S=JNq0v_sEE+9PHXg@mail.gmail.com Backpatch: 9.4-, where logical decoding was introduced --- src/backend/replication/logical/reorderbuffer.c | 7 ++++--- src/include/replication/reorderbuffer.h | 9 +++++++++ 2 files changed, 13 insertions(+), 3 deletions(-) diff --git a/src/backend/replication/logical/reorderbuffer.c b/src/backend/replication/logical/reorderbuffer.c index 524946a2a27..8f4f7f842bc 100644 --- a/src/backend/replication/logical/reorderbuffer.c +++ b/src/backend/replication/logical/reorderbuffer.c @@ -893,7 +893,7 @@ ReorderBufferIterTXNInit(ReorderBuffer *rb, ReorderBufferTXN *txn) { ReorderBufferChange *cur_change; - if (txn->nentries != txn->nentries_mem) + if (txn->serialized) { /* serialize remaining changes */ ReorderBufferSerializeTXN(rb, txn); @@ -922,7 +922,7 @@ ReorderBufferIterTXNInit(ReorderBuffer *rb, ReorderBufferTXN *txn) { ReorderBufferChange *cur_change; - if (cur_txn->nentries != cur_txn->nentries_mem) + if (cur_txn->serialized) { /* serialize remaining changes */ ReorderBufferSerializeTXN(rb, cur_txn); @@ -1142,7 +1142,7 @@ ReorderBufferCleanupTXN(ReorderBuffer *rb, ReorderBufferTXN *txn) Assert(found); /* remove entries spilled to disk */ - if (txn->nentries != txn->nentries_mem) + if (txn->serialized) ReorderBufferRestoreCleanup(rb, txn); /* deallocate */ @@ -2124,6 +2124,7 @@ ReorderBufferSerializeTXN(ReorderBuffer *rb, ReorderBufferTXN *txn) Assert(spilled == txn->nentries_mem); Assert(dlist_is_empty(&txn->changes)); txn->nentries_mem = 0; + txn->serialized = true; if (fd != -1) CloseTransientFile(fd); diff --git a/src/include/replication/reorderbuffer.h b/src/include/replication/reorderbuffer.h index 17e47b385b7..8d8d418e8e3 100644 --- a/src/include/replication/reorderbuffer.h +++ b/src/include/replication/reorderbuffer.h @@ -212,6 +212,15 @@ typedef struct ReorderBufferTXN */ uint64 nentries_mem; + /* + * Has this transaction been spilled to disk? It's not always possible to + * deduce that fact by comparing nentries with nentries_mem, because + * e.g. subtransactions of a large transaction might get serialized + * together with the parent - if they're restored to memory they'd have + * nentries_mem == nentries. + */ + bool serialized; + /* * List of ReorderBufferChange structs, including new Snapshots and new * CommandIds