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17 | 17 | #include"miscadmin.h" |
18 | 18 | #include"optimizer/planner.h" |
19 | 19 | #include"pgstat.h" |
| 20 | +#include"postmaster/autovacuum.h" |
| 21 | +#ifPG_VERSION_NUM >=120000 |
| 22 | +#include"replication/walsender.h" |
| 23 | +#endif |
20 | 24 | #include"storage/ipc.h" |
21 | 25 | #include"storage/pg_shmem.h" |
22 | 26 | #include"storage/procarray.h" |
@@ -66,20 +70,46 @@ static void pgws_ExecutorEnd(QueryDesc *queryDesc); |
66 | 70 |
|
67 | 71 | /* |
68 | 72 | * Calculate max processes count. |
69 | | - * Look at InitProcGlobal (proc.c) and TotalProcs variable in it |
70 | | - * if something wrong here. |
| 73 | + * |
| 74 | + * The value has to be in sync with ProcGlobal->allProcCount, initialized in |
| 75 | + * InitProcGlobal() (proc.c). |
| 76 | + * |
| 77 | + * We calculate the value here as it won't initialized when we need need |
| 78 | + * it during _PG_init(). |
| 79 | + * |
| 80 | + * Note that the value returned during _PG_init() might be different from the |
| 81 | + * value returned later if some third-party modules change one of the |
| 82 | + * underlying GUC. This isn't ideal but can't lead to a crash, as the value |
| 83 | + * returned during _PG_init() is only used to ask for additional shmem with |
| 84 | + * RequestAddinShmemSpace(), and postgres has an extra 100kB of shmem to |
| 85 | + * compensate some small unaccounted usage. So if the value later changes, we |
| 86 | + * will allocate and initialize the new (and correct) memory size, which |
| 87 | + * will either work thanks for the extra 100kB of shmem, of fail (and prevent |
| 88 | + * postgres startup) due to an out of shared memory error. |
71 | 89 | */ |
72 | 90 | staticint |
73 | 91 | get_max_procs_count(void) |
74 | 92 | { |
75 | 93 | intcount=0; |
76 | 94 |
|
77 | | -/* MyProcs, including autovacuum workers and launcher */ |
78 | | -count+=MaxBackends; |
| 95 | +/* |
| 96 | + * MaxBackends: bgworkers, autovacuum workers and launcher. |
| 97 | + * This has to be in sync with the value computed in |
| 98 | + * InitializeMaxBackends() (postinit.c) |
| 99 | + */ |
| 100 | +count+=MaxConnections+autovacuum_max_workers+1 |
| 101 | ++max_worker_processes; |
| 102 | + |
| 103 | +/* |
| 104 | + * Starting with pg12, wal senders aren't part of MaxConnections anymore |
| 105 | + * and have to be accounted for. |
| 106 | + */ |
| 107 | +#ifPG_VERSION_NUM >=120000 |
| 108 | +count+=max_wal_senders; |
| 109 | +#endif |
| 110 | + |
79 | 111 | /* AuxiliaryProcs */ |
80 | 112 | count+=NUM_AUXILIARY_PROCS; |
81 | | -/* Prepared xacts */ |
82 | | -count+=max_prepared_xacts; |
83 | 113 |
|
84 | 114 | returncount; |
85 | 115 | } |
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