From 0477203b123d96bd5dfa1d47f0509aa1a156ddcd 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_parameters.dat | 8 ++++++++ src/backend/utils/misc/guc_tables.c | 9 +++++++++ src/backend/utils/misc/postgresql.conf.sample | 1 + src/include/access/parallel.h | 10 ++++++++++ src/include/utils/guc.h | 1 + 7 files changed, 66 insertions(+) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index 0fad34da6eb..5332993631d 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -8066,6 +8066,24 @@ 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 01a89104ef0..817edfdd62a 100644 --- a/src/backend/access/transam/parallel.c +++ b/src/backend/access/transam/parallel.c @@ -1670,3 +1670,22 @@ 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_parameters.dat b/src/backend/utils/misc/guc_parameters.dat index 7c60b125564..a096f72fe57 100644 --- a/src/backend/utils/misc/guc_parameters.dat +++ b/src/backend/utils/misc/guc_parameters.dat @@ -1700,6 +1700,14 @@ options => 'server_message_level_options', }, +{ name => 'log_parallel_workers', type => 'enum', context => 'PGC_SUSET', group => 'LOGGING_WHAT', + short_desc => 'Log information about parallel worker usage.', + long_desc => '"none" doesn\'t log anything, "all" logs all parallel worker usage and "shortage" logs only when the planned workers couldn\'t be acquired', + variable => 'log_parallel_workers', + boot_val => 'LOG_PARALLEL_WORKERS_NONE', + options => 'log_parallel_workers_options', +}, + { name => 'log_parameter_max_length', type => 'int', context => 'PGC_SUSET', group => 'LOGGING_WHAT', short_desc => 'Sets the maximum length in bytes of data logged for bind parameter values when logging statements.', long_desc => '-1 means log values in full.', diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 73ff6ad0a32..feee4fee7a6 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" @@ -491,6 +492,13 @@ static const struct config_enum_entry file_copy_method_options[] = { {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} +}; + /* * Options for enum values stored in other modules */ @@ -544,6 +552,7 @@ 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; diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index dc9e2255f8a..8dcba3aae4a 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -646,6 +646,7 @@ #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 01bdf2bec1f..623ca839001 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 bf39878c43e..aee4012950d 100644 --- a/src/include/utils/guc.h +++ b/src/include/utils/guc.h @@ -303,6 +303,7 @@ 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; -- 2.47.3