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.

diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index 5d7888ade1807e81d68b150c4cd1e0ce2722e3d9..1dac6954885cdc7295817cc09ecf662256927e08 100644 (file)
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -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;

diff --git a/src/backend/storage/file/fd.c b/src/backend/storage/file/fd.c
index 8f442f0a7f81745c55a9fdae66737f088515d300..fa376ae4bb3d1a56669552e18b174beea9688ef8 100644 (file)
--- a/src/backend/storage/file/fd.c
+++ b/src/backend/storage/file/fd.c
@@ -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.... */

diff --git a/src/include/storage/fd.h b/src/include/storage/fd.h
index 22e7fe89efea273798e954bdccef25e69e579a73..bad9f10c62ec84351bf191eecde7ad99d433d867 100644 (file)
--- a/src/include/storage/fd.h
+++ b/src/include/storage/fd.h
@@ -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