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Inherit max_safe_fds to child processes in EXEC_BACKEND mode. 

Postmaster sets max_safe_fds by testing how many open file descriptors it
can open, and that is normally inherited by all child processes at fork().
Not so on EXEC_BACKEND, ie. Windows, however. Because of that, we
effectively ignored max_files_per_process on Windows, and always assumed
a conservative default of 32 simultaneous open files. That could have an
impact on performance, if you need to access a lot of different files
in a query. After this patch, the value is passed to child processes by
save/restore_backend_variables() among many other global variables.

It has been like this forever, but given the lack of complaints about it,
I'm not backpatching this.
This commit is contained in:
Heikki Linnakangas 2012-03-29 08:19:11 +03:00
parent d2c1740dc2
commit 5762a4d909
3 changed files with 9 additions and 1 deletions
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3
src/backend/postmaster/postmaster.c
View File

@ -438,6 +438,7 @@ typedef struct
TimestampTz PgReloadTime;
bool redirection_done;
bool IsBinaryUpgrade;
int max_safe_fds;
#ifdef WIN32
HANDLE PostmasterHandle;
HANDLE initial_signal_pipe;
@ -4741,6 +4742,7 @@ save_backend_variables(BackendParameters *param, Port *port,
param->redirection_done = redirection_done;
param->IsBinaryUpgrade = IsBinaryUpgrade;
param->max_safe_fds = max_safe_fds;
#ifdef WIN32
param->PostmasterHandle = PostmasterHandle;
@ -4964,6 +4966,7 @@ restore_backend_variables(BackendParameters *param, Port *port)
redirection_done = param->redirection_done;
IsBinaryUpgrade = param->IsBinaryUpgrade;
max_safe_fds = param->max_safe_fds;
#ifdef WIN32
PostmasterHandle = param->PostmasterHandle;

2
src/backend/storage/file/fd.c
View File

@ -103,7 +103,7 @@ int max_files_per_process = 1000;
* Note: the value of max_files_per_process is taken into account while
* setting this variable, and so need not be tested separately.
*/
static int max_safe_fds = 32; /* default if not changed */
int max_safe_fds = 32; /* default if not changed */
/* Debugging.... */

5
src/include/storage/fd.h
View File

@ -53,6 +53,11 @@ typedef int File;
/* GUC parameter */
extern int max_files_per_process;
/*
* This is private to fd.c, but exported for save/restore_backend_variables()
*/
extern int max_safe_fds;
/*
* prototypes for functions in fd.c