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 ea9e88423e0c5da11d2112670f0fdc4f02404c9f..d1d1716c1014ef11d8892abab604fac977151189 100644 (file)
--- a/src/backend/executor/nodeHash.c
+++ b/src/backend/executor/nodeHash.c
@@ -667,6 +667,9 @@ ExecHashIncreaseNumBatches(HashJoinTable hashtable)
            }
 
            tuple = nexttuple;
+
+           /* allow this loop to be cancellable */
+           CHECK_FOR_INTERRUPTS();
        }
    }
 
@@ -1438,6 +1441,9 @@ 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 7eec3f333deff3d92d17afb71b383c16e0d385ab..27e60f09f716e3bd1990bc0f5ea8528edbd49dfb 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