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 6375d9bfda7ee2818fe59540d1c24be21e49be40..ebfe9278b6a3d45bd83b4f71a7e185bc97f8adaf 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 369e666f8850df141b17ece36d172cc98c975bd4..c4d4c600312428df269247cc346c7be3ea1d79d3 100644 (file)
--- a/src/backend/executor/nodeHashjoin.c
+++ b/src/backend/executor/nodeHashjoin.c
@@ -911,6 +911,13 @@ 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