diff options
Diffstat (limited to 'src/backend/storage/lmgr/deadlock.c')
| -rw-r--r-- | src/backend/storage/lmgr/deadlock.c | 21 |
1 files changed, 15 insertions, 6 deletions
diff --git a/src/backend/storage/lmgr/deadlock.c b/src/backend/storage/lmgr/deadlock.c index 69f678b5f8d..3f3e24fda22 100644 --- a/src/backend/storage/lmgr/deadlock.c +++ b/src/backend/storage/lmgr/deadlock.c @@ -33,12 +33,21 @@ #include "utils/memutils.h" -/* One edge in the waits-for graph */ +/* + * One edge in the waits-for graph. + * + * waiter and blocker may or may not be members of a lock group, but if either + * is, it will be the leader rather than any other member of the lock group. + * The group leaders act as representatives of the whole group even though + * those particular processes need not be waiting at all. There will be at + * least one member of the waiter's lock group on the wait queue for the given + * lock, maybe more. + */ typedef struct { - PGPROC *waiter; /* the waiting process */ - PGPROC *blocker; /* the process it is waiting for */ - LOCK *lock; /* the lock it is waiting for */ + PGPROC *waiter; /* the leader of the waiting lock group */ + PGPROC *blocker; /* the leader of the group it is waiting for */ + LOCK *lock; /* the lock being waited for */ int pred; /* workspace for TopoSort */ int link; /* workspace for TopoSort */ } EDGE; @@ -1006,8 +1015,8 @@ TopoSort(LOCK *lock, return false; /* - * Output everything in the lock group. There's no point in outputing - * an ordering where members of the same lock group are not + * Output everything in the lock group. There's no point in + * outputting an ordering where members of the same lock group are not * consecutive on the wait queue: if some other waiter is between two * requests that belong to the same group, then either it conflicts * with both of them and is certainly not a solution; or it conflicts |