Make sure that hash join's bulk-tuple-transfer loops are interruptible.

The loops in ExecHashJoinNewBatch(), ExecHashIncreaseNumBatches(), and
ExecHashRemoveNextSkewBucket() are all capable of iterating over many
tuples without ever doing a CHECK_FOR_INTERRUPTS, so that the backend
might fail to respond to SIGINT or SIGTERM for an unreasonably long time.
Fix that.  In the case of ExecHashJoinNewBatch(), it seems useful to put
the added CHECK_FOR_INTERRUPTS into ExecHashJoinGetSavedTuple() rather
than directly in the loop, because that will also ensure that both
principal code paths through ExecHashJoinOuterGetTuple() will do a
CHECK_FOR_INTERRUPTS, which seems like a good idea to avoid surprises.

Back-patch to all supported branches.

Tom Lane and Thomas Munro

Discussion: https://postgr.es/m/6044.1487121720@sss.pgh.pa.us

diff --git a/src/backend/executor/nodeHash.c b/src/backend/executor/nodeHash.c
index af5934d2bcfcf804d2840425df927d7946b4760f..e695d8834b550e6408e13fca4a05eea8d48b10a6 100644 (file)
--- a/src/backend/executor/nodeHash.c
+++ b/src/backend/executor/nodeHash.c
@@ -720,6 +720,9 @@ ExecHashIncreaseNumBatches(HashJoinTable hashtable)
 
                        /* next tuple in this chunk */
                        idx += MAXALIGN(hashTupleSize);
+
+                       /* allow this loop to be cancellable */
+                       CHECK_FOR_INTERRUPTS();
                }
 
                /* we're done with this chunk - free it and proceed to the next one */
@@ -1599,6 +1602,9 @@ ExecHashRemoveNextSkewBucket(HashJoinTable hashtable)
                }
 
                hashTuple = nextHashTuple;
+
+               /* allow this loop to be cancellable */
+               CHECK_FOR_INTERRUPTS();
        }
 
        /*

diff --git a/src/backend/executor/nodeHashjoin.c b/src/backend/executor/nodeHashjoin.c
index 8a04294b40207e4ff2c33ad0499a21bd45994f67..c50d93f43dbe19164e7cae4810bde02e83493d98 100644 (file)
--- a/src/backend/executor/nodeHashjoin.c
+++ b/src/backend/executor/nodeHashjoin.c
@@ -856,6 +856,13 @@ ExecHashJoinGetSavedTuple(HashJoinState *hjstate,
        size_t          nread;
        MinimalTuple tuple;
 
+       /*
+        * We check for interrupts here because this is typically taken as an
+        * alternative code path to an ExecProcNode() call, which would include
+        * such a check.
+        */
+       CHECK_FOR_INTERRUPTS();
+
        /*
         * Since both the hash value and the MinimalTuple length word are uint32,
         * we can read them both in one BufFileRead() call without any type