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Pass MyPMChildSlot as an explicit argument to child process

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All the other global variables passed from postmaster to child have
the same value in all the processes, while MyPMChildSlot is more like
a parameter to each child process.

Reviewed-by: Andres Freund <andres@anarazel.de>
Discussion: https://www.postgresql.org/message-id/a102f15f-eac4-4ff2-af02-f9ff209ec66f@iki.fi
This commit is contained in:
Heikki Linnakangas 2024-11-14 16:12:32 +02:00
parent a78af04270
commit 5b00786857
4 changed files with 33 additions and 22 deletions
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37
src/backend/postmaster/launch_backend.c
View File

@ -88,7 +88,6 @@ typedef int InheritableSocket;
typedef struct typedef struct
{ {
char DataDir[MAXPGPATH]; char DataDir[MAXPGPATH];
int MyPMChildSlot;
#ifndef WIN32 #ifndef WIN32
unsigned long UsedShmemSegID; unsigned long UsedShmemSegID;
#else #else
@ -130,6 +129,8 @@ typedef struct
char my_exec_path[MAXPGPATH]; char my_exec_path[MAXPGPATH];
char pkglib_path[MAXPGPATH]; char pkglib_path[MAXPGPATH];
int MyPMChildSlot;
/* /*
* These are only used by backend processes, but are here because passing * These are only used by backend processes, but are here because passing
* a socket needs some special handling on Windows. 'client_sock' is an * a socket needs some special handling on Windows. 'client_sock' is an
@ -151,13 +152,16 @@ typedef struct
static void read_backend_variables(char *id, char **startup_data, size_t *startup_data_len); static void read_backend_variables(char *id, char **startup_data, size_t *startup_data_len);
static void restore_backend_variables(BackendParameters *param); static void restore_backend_variables(BackendParameters *param);
static bool save_backend_variables(BackendParameters *param, ClientSocket *client_sock, static bool save_backend_variables(BackendParameters *param, int child_slot,
ClientSocket *client_sock,
#ifdef WIN32 #ifdef WIN32
HANDLE childProcess, pid_t childPid, HANDLE childProcess, pid_t childPid,
#endif #endif
char *startup_data, size_t startup_data_len); char *startup_data, size_t startup_data_len);
static pid_t internal_forkexec(const char *child_kind, char *startup_data, size_t startup_data_len, ClientSocket *client_sock); static pid_t internal_forkexec(const char *child_kind, int child_slot,
char *startup_data, size_t startup_data_len,
ClientSocket *client_sock);
#endif /* EXEC_BACKEND */ #endif /* EXEC_BACKEND */
@ -215,11 +219,12 @@ PostmasterChildName(BackendType child_type)
* appropriate, and fds and other resources that we've inherited from * appropriate, and fds and other resources that we've inherited from
* postmaster that are not needed in a child process have been closed. * postmaster that are not needed in a child process have been closed.
* *
* 'startup_data' is an optional contiguous chunk of data that is passed to * 'child_slot' is the PMChildFlags array index reserved for the child
* the child process. * process. 'startup_data' is an optional contiguous chunk of data that is
* passed to the child process.
*/ */
pid_t pid_t
postmaster_child_launch(BackendType child_type, postmaster_child_launch(BackendType child_type, int child_slot,
char *startup_data, size_t startup_data_len, char *startup_data, size_t startup_data_len,
ClientSocket *client_sock) ClientSocket *client_sock)
{ {
@ -228,7 +233,7 @@ postmaster_child_launch(BackendType child_type,
Assert(IsPostmasterEnvironment && !IsUnderPostmaster); Assert(IsPostmasterEnvironment && !IsUnderPostmaster);
#ifdef EXEC_BACKEND #ifdef EXEC_BACKEND
pid = internal_forkexec(child_process_kinds[child_type].name, pid = internal_forkexec(child_process_kinds[child_type].name, child_slot,
startup_data, startup_data_len, client_sock); startup_data, startup_data_len, client_sock);
/* the child process will arrive in SubPostmasterMain */ /* the child process will arrive in SubPostmasterMain */
#else /* !EXEC_BACKEND */ #else /* !EXEC_BACKEND */
@ -256,6 +261,7 @@ postmaster_child_launch(BackendType child_type,
*/ */
MemoryContextSwitchTo(TopMemoryContext); MemoryContextSwitchTo(TopMemoryContext);
MyPMChildSlot = child_slot;
if (client_sock) if (client_sock)
{ {
MyClientSocket = palloc(sizeof(ClientSocket)); MyClientSocket = palloc(sizeof(ClientSocket));
@ -282,7 +288,8 @@ postmaster_child_launch(BackendType child_type,
* - fork():s, and then exec():s the child process * - fork():s, and then exec():s the child process
*/ */
static pid_t static pid_t
internal_forkexec(const char *child_kind, char *startup_data, size_t startup_data_len, ClientSocket *client_sock) internal_forkexec(const char *child_kind, int child_slot,
char *startup_data, size_t startup_data_len, ClientSocket *client_sock)
{ {
static unsigned long tmpBackendFileNum = 0; static unsigned long tmpBackendFileNum = 0;
pid_t pid; pid_t pid;
@ -302,7 +309,7 @@ internal_forkexec(const char *child_kind, char *startup_data, size_t startup_dat
*/ */
paramsz = SizeOfBackendParameters(startup_data_len); paramsz = SizeOfBackendParameters(startup_data_len);
param = palloc0(paramsz); param = palloc0(paramsz);
if (!save_backend_variables(param, client_sock, startup_data, startup_data_len)) if (!save_backend_variables(param, child_slot, client_sock, startup_data, startup_data_len))
{ {
pfree(param); pfree(param);
return -1; /* log made by save_backend_variables */ return -1; /* log made by save_backend_variables */
@ -391,7 +398,8 @@ internal_forkexec(const char *child_kind, char *startup_data, size_t startup_dat
* file is complete. * file is complete.
*/ */
static pid_t static pid_t
internal_forkexec(const char *child_kind, char *startup_data, size_t startup_data_len, ClientSocket *client_sock) internal_forkexec(const char *child_kind, int child_slot,
char *startup_data, size_t startup_data_len, ClientSocket *client_sock)
{ {
int retry_count = 0; int retry_count = 0;
STARTUPINFO si; STARTUPINFO si;
@ -472,7 +480,9 @@ retry:
return -1; return -1;
} }
if (!save_backend_variables(param, client_sock, pi.hProcess, pi.dwProcessId, startup_data, startup_data_len)) if (!save_backend_variables(param, child_slot, client_sock,
pi.hProcess, pi.dwProcessId,
startup_data, startup_data_len))
{ {
/* /*
* log made by save_backend_variables, but we have to clean up the * log made by save_backend_variables, but we have to clean up the
@ -684,7 +694,8 @@ static void read_inheritable_socket(SOCKET *dest, InheritableSocket *src);
/* Save critical backend variables into the BackendParameters struct */ /* Save critical backend variables into the BackendParameters struct */
static bool static bool
save_backend_variables(BackendParameters *param, ClientSocket *client_sock, save_backend_variables(BackendParameters *param,
int child_slot, ClientSocket *client_sock,
#ifdef WIN32 #ifdef WIN32
HANDLE childProcess, pid_t childPid, HANDLE childProcess, pid_t childPid,
#endif #endif
@ -701,7 +712,7 @@ save_backend_variables(BackendParameters *param, ClientSocket *client_sock,
strlcpy(param->DataDir, DataDir, MAXPGPATH); strlcpy(param->DataDir, DataDir, MAXPGPATH);
param->MyPMChildSlot = MyPMChildSlot; param->MyPMChildSlot = child_slot;
#ifdef WIN32 #ifdef WIN32
param->ShmemProtectiveRegion = ShmemProtectiveRegion; param->ShmemProtectiveRegion = ShmemProtectiveRegion;

10
src/backend/postmaster/postmaster.c
View File

@ -3374,8 +3374,7 @@ BackendStartup(ClientSocket *client_sock)
/* Hasn't asked to be notified about any bgworkers yet */ /* Hasn't asked to be notified about any bgworkers yet */
bn->bgworker_notify = false; bn->bgworker_notify = false;
MyPMChildSlot = bn->child_slot; pid = postmaster_child_launch(bn->bkend_type, bn->child_slot,
pid = postmaster_child_launch(bn->bkend_type,
(char *) &startup_data, sizeof(startup_data), (char *) &startup_data, sizeof(startup_data),
client_sock); client_sock);
if (pid < 0) if (pid < 0)
@ -3700,8 +3699,7 @@ StartChildProcess(BackendType type)
return NULL; return NULL;
} }
MyPMChildSlot = pmchild->child_slot; pid = postmaster_child_launch(type, pmchild->child_slot, NULL, 0, NULL);
pid = postmaster_child_launch(type, NULL, 0, NULL);
if (pid < 0) if (pid < 0)
{ {
/* in parent, fork failed */ /* in parent, fork failed */
@ -3878,8 +3876,8 @@ StartBackgroundWorker(RegisteredBgWorker *rw)
(errmsg_internal("starting background worker process \"%s\"", (errmsg_internal("starting background worker process \"%s\"",
rw->rw_worker.bgw_name))); rw->rw_worker.bgw_name)));
MyPMChildSlot = bn->child_slot; worker_pid = postmaster_child_launch(B_BG_WORKER, bn->child_slot,
worker_pid = postmaster_child_launch(B_BG_WORKER, (char *) &rw->rw_worker, sizeof(BackgroundWorker), NULL); (char *) &rw->rw_worker, sizeof(BackgroundWorker), NULL);
if (worker_pid == -1) if (worker_pid == -1)
{ {
/* in postmaster, fork failed ... */ /* in postmaster, fork failed ... */

7
src/backend/postmaster/syslogger.c
View File

@ -694,14 +694,15 @@ SysLogger_Start(int child_slot)
pfree(filename); pfree(filename);
} }
MyPMChildSlot = child_slot;
#ifdef EXEC_BACKEND #ifdef EXEC_BACKEND
startup_data.syslogFile = syslogger_fdget(syslogFile); startup_data.syslogFile = syslogger_fdget(syslogFile);
startup_data.csvlogFile = syslogger_fdget(csvlogFile); startup_data.csvlogFile = syslogger_fdget(csvlogFile);
startup_data.jsonlogFile = syslogger_fdget(jsonlogFile); startup_data.jsonlogFile = syslogger_fdget(jsonlogFile);
sysloggerPid = postmaster_child_launch(B_LOGGER, (char *) &startup_data, sizeof(startup_data), NULL); sysloggerPid = postmaster_child_launch(B_LOGGER, child_slot,
(char *) &startup_data, sizeof(startup_data), NULL);
#else #else
sysloggerPid = postmaster_child_launch(B_LOGGER, NULL, 0, NULL); sysloggerPid = postmaster_child_launch(B_LOGGER, child_slot,
NULL, 0, NULL);
#endif /* EXEC_BACKEND */ #endif /* EXEC_BACKEND */
if (sysloggerPid == -1) if (sysloggerPid == -1)

1
src/include/postmaster/postmaster.h
View File

@ -108,6 +108,7 @@ extern PGDLLIMPORT struct ClientSocket *MyClientSocket;
/* prototypes for functions in launch_backend.c */ /* prototypes for functions in launch_backend.c */
extern pid_t postmaster_child_launch(BackendType child_type, extern pid_t postmaster_child_launch(BackendType child_type,
int child_slot,
char *startup_data, char *startup_data,
size_t startup_data_len, size_t startup_data_len,
struct ClientSocket *client_sock); struct ClientSocket *client_sock);