From 59cd090e78a5833b901ad662d6ae1ae936c3172d Mon Sep 17 00:00:00 2001 From: benoit Date: Tue, 8 Oct 2024 12:39:41 +0200 Subject: [PATCH 1/3] Add a guc for parallel worker logging The new guc log_parallel_workers controls whether a log message is produced to display information on the number of workers spawned when a parallel query or utility is executed. The default value is `none` which disables logging. `all` displays information for all parallel queries, whereas `shortage` displays information only when the number of workers launched is lower than the number of planned workers. This new parameter can help database administrators and developers diagnose performance issues related to parallelism and optimize the configuration of the system accordingly. --- doc/src/sgml/config.sgml | 18 ++++++++++++++++++ src/backend/access/transam/parallel.c | 19 +++++++++++++++++++ src/backend/utils/misc/guc_tables.c | 19 +++++++++++++++++++ src/backend/utils/misc/postgresql.conf.sample | 1 + src/include/access/parallel.h | 10 ++++++++++ src/include/utils/guc.h | 1 + 6 files changed, 68 insertions(+) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index c1674c22cb2..b1345d15a84 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -7950,6 +7950,24 @@ log_line_prefix = '%m [%p] %q%u@%d/%a ' + + log_parallel_workers (enum) + + log_parallel_workers configuration parameter + + + + + Controls whether a log message about the number of workers is emitted during the + execution of a parallel query or utility statement. The default value is + none which disables logging. all emits + information for all parallel queries or utilities, whereas shortage + emits information only when the number of workers launched is lower than the number + of planned workers. + + + + log_parameter_max_length (integer) diff --git a/src/backend/access/transam/parallel.c b/src/backend/access/transam/parallel.c index 94db1ec3012..77a8deff30d 100644 --- a/src/backend/access/transam/parallel.c +++ b/src/backend/access/transam/parallel.c @@ -1663,3 +1663,22 @@ LookupParallelWorkerFunction(const char *libraryname, const char *funcname) return (parallel_worker_main_type) load_external_function(libraryname, funcname, true, NULL); } + +/* + * If required, emit information about parallel workers usage in + * the logs. + */ +void +LogParallelWorkersIfNeeded(int log_parallel_workers, + int parallel_workers_to_launch, + int parallel_workers_launched) +{ + if ((log_parallel_workers == LOG_PARALLEL_WORKERS_ALL && + parallel_workers_to_launch > 0) || + (log_parallel_workers == LOG_PARALLEL_WORKERS_SHORTAGE && + parallel_workers_to_launch != parallel_workers_launched)) + ereport(LOG, + (errmsg("launched %i parallel workers (planned: %i)", + parallel_workers_launched, + parallel_workers_to_launch))); +} diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 60b12446a1c..0e7b3960ad5 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -31,6 +31,7 @@ #include "access/commit_ts.h" #include "access/gin.h" +#include "access/parallel.h" #include "access/slru.h" #include "access/toast_compression.h" #include "access/twophase.h" @@ -432,6 +433,13 @@ static const struct config_enum_entry debug_logical_replication_streaming_option {NULL, 0, false} }; +static const struct config_enum_entry log_parallel_workers_options[] = { + {"none", LOG_PARALLEL_WORKERS_NONE, false}, + {"all", LOG_PARALLEL_WORKERS_ALL, false}, + {"shortage", LOG_PARALLEL_WORKERS_SHORTAGE, false}, + {NULL, 0, false} +}; + StaticAssertDecl(lengthof(ssl_protocol_versions_info) == (PG_TLS1_3_VERSION + 2), "array length mismatch"); @@ -543,6 +551,7 @@ int log_min_duration_statement = -1; int log_parameter_max_length = -1; int log_parameter_max_length_on_error = 0; int log_temp_files = -1; +int log_parallel_workers = LOG_PARALLEL_WORKERS_NONE; double log_statement_sample_rate = 1.0; double log_xact_sample_rate = 0; char *backtrace_functions; @@ -5362,6 +5371,16 @@ struct config_enum ConfigureNamesEnum[] = NULL, NULL, NULL }, + { + {"log_parallel_workers", PGC_SUSET, LOGGING_WHAT, + gettext_noop("Log information about parallel worker usage"), + NULL + }, + &log_parallel_workers, + LOG_PARALLEL_WORKERS_NONE, log_parallel_workers_options, + NULL, NULL, NULL + }, + { {"ssl_min_protocol_version", PGC_SIGHUP, CONN_AUTH_SSL, gettext_noop("Sets the minimum SSL/TLS protocol version to use."), diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 34826d01380..1ccae086b88 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -642,6 +642,7 @@ #log_temp_files = -1 # log temporary files equal or larger # than the specified size in kilobytes; # -1 disables, 0 logs all temp files +#log_parallel_workers = none # none, all, shortage #log_timezone = 'GMT' # - Process Title - diff --git a/src/include/access/parallel.h b/src/include/access/parallel.h index f37be6d5690..f865cd755e3 100644 --- a/src/include/access/parallel.h +++ b/src/include/access/parallel.h @@ -53,6 +53,12 @@ typedef struct ParallelWorkerContext shm_toc *toc; } ParallelWorkerContext; +typedef enum { + LOG_PARALLEL_WORKERS_NONE=0, + LOG_PARALLEL_WORKERS_ALL, + LOG_PARALLEL_WORKERS_SHORTAGE, +} log_parallel_workers_option_list; + extern PGDLLIMPORT volatile sig_atomic_t ParallelMessagePending; extern PGDLLIMPORT int ParallelWorkerNumber; extern PGDLLIMPORT bool InitializingParallelWorker; @@ -78,4 +84,8 @@ extern void ParallelWorkerReportLastRecEnd(XLogRecPtr last_xlog_end); extern void ParallelWorkerMain(Datum main_arg); +extern void LogParallelWorkersIfNeeded(int log_parallel_workers, + int parallel_workers_to_launch, + int parallel_workers_launched); + #endif /* PARALLEL_H */ diff --git a/src/include/utils/guc.h b/src/include/utils/guc.h index f619100467d..7986dc3e541 100644 --- a/src/include/utils/guc.h +++ b/src/include/utils/guc.h @@ -279,6 +279,7 @@ extern PGDLLIMPORT int log_temp_files; extern PGDLLIMPORT double log_statement_sample_rate; extern PGDLLIMPORT double log_xact_sample_rate; extern PGDLLIMPORT char *backtrace_functions; +extern PGDLLIMPORT int log_parallel_workers; extern PGDLLIMPORT int temp_file_limit; -- 2.48.1