prefork.c revision d7d24786c80ad1ae337b916a0a44b2a7b8fcb54d
/* ====================================================================
* The Apache Software License, Version 1.1
*
* Copyright (c) 2000-2001 The Apache Software Foundation. All rights
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* distribution.
*
* 3. The end-user documentation included with the redistribution,
* if any, must include the following acknowledgment:
* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
* Alternately, this acknowledgment may appear in the software itself,
* if and wherever such third-party acknowledgments normally appear.
*
* 4. The names "Apache" and "Apache Software Foundation" must
* not be used to endorse or promote products derived from this
* software without prior written permission. For written
* permission, please contact apache@apache.org.
*
* 5. Products derived from this software may not be called "Apache",
* nor may "Apache" appear in their name, without prior written
* permission of the Apache Software Foundation.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
*
* Portions of this software are based upon public domain software
* originally written at the National Center for Supercomputing Applications,
* University of Illinois, Urbana-Champaign.
*/
#include "apr.h"
#include "apr_portable.h"
#include "apr_strings.h"
#include "apr_thread_proc.h"
#include "apr_signal.h"
#define APR_WANT_STDIO
#define APR_WANT_STRFUNC
#include "apr_want.h"
#include <unistd.h>
#endif
#endif
#define CORE_PRIVATE
#include "ap_config.h"
#include "httpd.h"
#include "mpm_default.h"
#include "http_main.h"
#include "http_log.h"
#include "http_config.h"
#include "http_core.h" /* for get_remote_host */
#include "http_connection.h"
#include "scoreboard.h"
#include "ap_mpm.h"
#include "unixd.h"
#include "mpm_common.h"
#include "ap_listen.h"
#include "ap_mmn.h"
#ifdef HAVE_BSTRING_H
#include <bstring.h> /* for IRIX, FD_SET calls bzero() */
#endif
#ifdef HAVE_TIME_H
#include <time.h>
#endif
#ifdef HAVE_SYS_PROCESSOR_H
#endif
#include <signal.h>
/* config globals */
int ap_threads_per_child=0; /* Worker threads per child */
static apr_lock_t *accept_lock;
static int ap_daemons_to_start=0;
static int ap_daemons_min_free=0;
static int ap_daemons_max_free=0;
static int ap_daemons_limit=0;
/*
* The max child slot ever assigned, preserved across restarts. Necessary
* to deal with MaxClients changes across AP_SIG_GRACEFUL restarts. We
* use this value to optimize routines that have to scan the entire scoreboard.
*/
int ap_max_daemons_limit = -1;
/* one_process --- debugging mode variable; can be set from the command line
* with the -X flag. If set, this gets you the child_main loop running
* in the process which originally started up (no detach, no make_child),
* which is a pretty nice debugging environment. (You'll get a SIGHUP
* early in standalone_main; just continue through. This is the server
* trying to kill off any child processes which it might have lying
* around --- Apache doesn't keep track of their pids, it just sends
* SIGHUP to the process group, ignoring it in the root process.
* Continue through and you'll be fine.).
*/
static int one_process = 0;
static pid_t parent_pid;
#ifndef MULTITHREAD
static int my_child_num;
#endif
#ifdef TPF
int tpf_child = 0;
#endif /* TPF */
static int die_now = 0;
#ifdef GPROF
/*
* change directory for gprof to plop the gmon.out file
* configure in httpd.conf:
* GprofDir logs/ -> $ServerRoot/logs/gmon.out
* GprofDir logs/% -> $ServerRoot/logs/gprof.$pid/gmon.out
*/
static void chdir_for_gprof(void)
{
const char *use_dir;
if(dir) {
char buf[512];
}
"gprof: error creating directory %s", dir);
}
}
else {
}
}
#else
#define chdir_for_gprof()
#endif
/* XXX - I don't know if TPF will ever use this module or not, so leave
* the ap_check_signals calls in but disable them - manoj */
#define ap_check_signals()
/* a clean exit from a child with proper cleanup */
static void clean_child_exit(int code)
{
if (pchild) {
}
}
static void expand_lock_fname(apr_pool_t *p)
{
/* XXXX possibly bogus cast */
}
/* Initialize mutex lock.
* Done by each child at its birth
*/
static void accept_mutex_child_init(apr_pool_t *p)
{
if (rv) {
"couldn't do child init for accept mutex");
}
}
/* Initialize mutex lock.
* Must be safe to call this on a restart.
*/
static void accept_mutex_init(apr_pool_t *p)
{
if (rv) {
}
if (ap_accept_lock_mech == APR_LOCK_DEFAULT ||
#else
if (ap_accept_lock_mech == APR_LOCK_SYSVSEM) {
#endif
if (rv != APR_SUCCESS) {
"Couldn't set permissions on cross-process lock");
}
}
}
static void accept_mutex_on(void)
{
if (rv != APR_SUCCESS) {
}
}
static void accept_mutex_off(void)
{
if (rv != APR_SUCCESS) {
}
}
/* On some architectures it's safe to do unserialized accept()s in the single
* Listen case. But it's never safe to do it in the case where there's
* multiple Listen statements. Define SINGLE_LISTEN_UNSERIALIZED_ACCEPT
* when it's safe in the single Listen case.
*/
#else
#endif
{
switch(query_code){
case AP_MPMQ_MAX_DAEMON_USED:
return APR_SUCCESS;
case AP_MPMQ_IS_THREADED:
return APR_SUCCESS;
case AP_MPMQ_IS_FORKED:
return APR_SUCCESS;
return APR_SUCCESS;
return APR_SUCCESS;
case AP_MPMQ_MAX_THREADS:
*result = 0;
return APR_SUCCESS;
return APR_SUCCESS;
*result = 0;
return APR_SUCCESS;
return APR_SUCCESS;
*result = 0;
return APR_SUCCESS;
return APR_SUCCESS;
case AP_MPMQ_MAX_DAEMONS:
return APR_SUCCESS;
}
return APR_ENOTIMPL;
}
#if defined(NEED_WAITPID)
/*
Systems without a real waitpid sometimes lose a child's exit while waiting
for another. Search through the scoreboard for missing children.
*/
{
int n, pid;
for (n = 0; n < ap_max_daemons_limit; ++n) {
/* just mark it as having a successful exit status */
*status = APR_PROC_EXIT;
*exitcode = 0;
return(pid);
}
}
return 0;
}
#endif
/* handle all varieties of core dumping signals */
static void sig_coredump(int sig)
{
if (ap_my_pid == parent_pid) {
0, ap_server_conf,
"seg fault or similar nasty error detected "
"in the parent process");
}
/* At this point we've got sig blocked, because we're still inside
* the signal handler. When we leave the signal handler it will
* be unblocked, and we'll take the signal... and coredump or whatever
* is appropriate for this particular Unix. In addition the parent
* will see the real signal we received -- whereas if we called
* abort() here, the parent would only see SIGABRT.
*/
}
/*****************************************************************
* Connection structures and accounting...
*/
{
clean_child_exit(0);
}
/* volatile just in case */
static int volatile shutdown_pending;
static int volatile restart_pending;
static int volatile is_graceful;
ap_generation_t volatile ap_my_generation=0;
{
if (shutdown_pending == 1) {
/* Um, is this _probably_ not an error, if the user has
* tried to do a shutdown twice quickly, so we won't
* worry about reporting it.
*/
return;
}
shutdown_pending = 1;
}
/* restart() is the signal handler for SIGHUP and AP_SIG_GRACEFUL
* in the parent process, unless running in ONE_PROCESS mode
*/
{
if (restart_pending == 1) {
/* Probably not an error - don't bother reporting it */
return;
}
restart_pending = 1;
}
}
static void set_signals(void)
{
#ifndef NO_USE_SIGACTION
if (!one_process) {
#if defined(SA_ONESHOT)
#elif defined(SA_RESETHAND)
#endif
#ifdef SIGBUS
#endif
#ifdef SIGABORT
#endif
#ifdef SIGABRT
#endif
#ifdef SIGILL
#endif
}
#ifdef SIGINT
#endif
#ifdef SIGXCPU
#endif
#ifdef SIGXFSZ
#endif
#ifdef SIGPIPE
#endif
/* we want to ignore HUPs and AP_SIG_GRACEFUL while we're busy
* processing one */
ap_log_error(APLOG_MARK, APLOG_WARNING, errno, ap_server_conf, "sigaction(" AP_SIG_GRACEFUL_STRING ")");
#else
if (!one_process) {
#ifdef SIGBUS
#endif /* SIGBUS */
#ifdef SIGABORT
#endif /* SIGABORT */
#ifdef SIGABRT
#endif /* SIGABRT */
#ifdef SIGILL
#endif /* SIGILL */
#ifdef SIGXCPU
#endif /* SIGXCPU */
#ifdef SIGXFSZ
#endif /* SIGXFSZ */
}
#ifdef SIGHUP
#endif /* SIGHUP */
#ifdef AP_SIG_GRACEFUL
#endif /* AP_SIG_GRACEFUL */
#ifdef SIGPIPE
#endif /* SIGPIPE */
#endif
}
/*****************************************************************
* Child process main loop.
* The following vars are static to avoid getting clobbered by longjmp();
* they are really private to child_main.
*/
static int requests_this_child;
static int num_listensocks = 0;
static ap_listen_rec *listensocks;
int ap_graceful_stop_signalled(void)
{
/* not ever called anymore... */
return 0;
}
static void child_main(int child_num_arg)
{
int i;
int curr_pollfd, last_pollfd = 0;
int offset;
void *csd;
requests_this_child = 0;
/* Get a sub context for global allocations in this child, so that
* we can have cleanups occur when the child exits.
*/
/* needs to be done before we switch UIDs so we have permissions */
if (unixd_setup_child()) {
}
(void) ap_update_child_status(AP_CHILD_THREAD_FROM_ID(my_child_num), SERVER_READY, (request_rec *) NULL);
/* Set up the pollfd array */
sizeof(*listensocks) * (num_listensocks));
}
for (i = 0; i < num_listensocks; i++)
while (!die_now) {
/*
* (Re)initialize this child to a pre-connection state.
*/
current_conn = NULL;
if ((ap_max_requests_per_child > 0
&& requests_this_child++ >= ap_max_requests_per_child)) {
clean_child_exit(0);
}
(void) ap_update_child_status(AP_CHILD_THREAD_FROM_ID(my_child_num), SERVER_READY, (request_rec *) NULL);
/*
* Wait for an acceptable connection to arrive.
*/
/* Lock around "accept", if necessary */
for (;;) {
apr_int32_t n;
if (ret != APR_SUCCESS) {
if (APR_STATUS_IS_EINTR(ret)) {
continue;
}
/* Single Unix documents select as returning errnos
* EBADF, EINTR, and EINVAL... and in none of those
* cases does it make sense to continue. In fact
* on Linux 2.0.x we seem to end up with EFAULT
* occasionally, and we'd loop forever due to it.
*/
"apr_poll: (listen)");
clean_child_exit(1);
}
if (num_listensocks == 1) {
offset = 0;
goto got_fd;
}
else {
/* find a listener */
do {
curr_pollfd++;
if (curr_pollfd >= num_listensocks) {
curr_pollfd = 0;
}
/* XXX: Should we check for POLLERR? */
if (event & APR_POLLIN) {
goto got_fd;
}
} while (curr_pollfd != last_pollfd);
}
continue;
}
/* if we accept() something we don't want to die, so we have to
* defer the exit
*/
for (;;) {
if (status == APR_SUCCESS) {
break;
}
if (status == APR_EGENERAL) {
}
}
/*
* We now have a connection, so set it up with the appropriate
*/
if (current_conn) {
}
/* Check the pod after processing a connection so that we'll go away
* if a graceful restart occurred while we were processing the
* connection. Otherwise, we won't wake up until a real connection
* comes in and we'll use the wrong config to process it and we may
* block in the wrong syscall (because the new generation is using a
* different accept mutex) and in general it is goofy.
*/
if (!ap_mpm_pod_check(pod)) {
die_now = 1;
}
}
clean_child_exit(0);
}
{
int pid;
}
if (one_process) {
/* Don't catch AP_SIG_GRACEFUL in ONE_PROCESS mode :) */
#ifdef SIGQUIT
#endif
}
(void) ap_update_child_status(AP_CHILD_THREAD_FROM_ID(slot), SERVER_STARTING, (request_rec *) NULL);
#ifdef _OSD_POSIX
/* BS2000 requires a "special" version of fork() before a setuid() call */
#else
#endif
/* fork didn't succeed. Fix the scoreboard or else
* it will say SERVER_STARTING forever and ever
*/
/* In case system resources are maxxed out, we don't want
Apache running away with the CPU trying to fork over and
over and over again. */
sleep(10);
return -1;
}
if (!pid) {
#ifdef HAVE_BINDPROCESSOR
/* by default AIX binds to a single processor
* this bit unbinds children which will then bind to another cpu
*/
}
#endif
/* Disable the parent's signal handlers and set up proper handling in
* the child.
*/
/* The child process doesn't do anything for AP_SIG_GRACEFUL.
* Instead, the pod is used for signalling graceful restart.
*/
}
#ifdef SCOREBOARD_FILE
sizeof(process_score));
#endif
return 0;
}
/* start up a bunch of children */
static void startup_children(int number_to_start)
{
int i;
for (i = 0; number_to_start && i < ap_daemons_limit; ++i) {
continue;
}
if (make_child(ap_server_conf, i) < 0) {
break;
}
}
}
/*
* idle_spawn_rate is the number of children that will be spawned on the
* next maintenance cycle if there aren't enough idle servers. It is
* doubled up to MAX_SPAWN_RATE, and reset only when a cycle goes by
* without the need to spawn.
*/
static int idle_spawn_rate = 1;
#ifndef MAX_SPAWN_RATE
#define MAX_SPAWN_RATE (32)
#endif
static int hold_off_on_exponential_spawning;
static void perform_idle_server_maintenance(apr_pool_t *p)
{
int i;
int to_kill;
int idle_count;
int free_length;
int free_slots[MAX_SPAWN_RATE];
int last_non_dead;
int total_non_dead;
/* initialize the free_list */
free_length = 0;
to_kill = -1;
idle_count = 0;
last_non_dead = -1;
total_non_dead = 0;
for (i = 0; i < ap_daemons_limit; ++i) {
int status;
break;
if (status == SERVER_DEAD) {
/* try to keep children numbers as low as possible */
if (free_length < idle_spawn_rate) {
free_slots[free_length] = i;
++free_length;
}
}
else {
/* We consider a starting server as idle because we started it
* at least a cycle ago, and if it still hasn't finished starting
* then we're just going to swamp things worse by forking more.
* So we hopefully won't need to fork more if we count it.
* This depends on the ordering of SERVER_READY and SERVER_STARTING.
*/
if (status <= SERVER_READY) {
++ idle_count;
/* always kill the highest numbered child if we have to...
* no really well thought out reason ... other than observing
* the server behaviour under linux where lower numbered children
* tend to service more hits (and hence are more likely to have
* their data in cpu caches).
*/
to_kill = i;
}
last_non_dead = i;
}
}
if (idle_count > ap_daemons_max_free) {
/* kill off one child... we use the pod because that'll cause it to
* shut down gracefully, in case it happened to pick up a request
* while we were counting
*/
idle_spawn_rate = 1;
}
else if (idle_count < ap_daemons_min_free) {
/* terminate the free list */
if (free_length == 0) {
/* only report this condition once */
static int reported = 0;
if (!reported) {
"server reached MaxClients setting, consider"
" raising the MaxClients setting");
reported = 1;
}
idle_spawn_rate = 1;
}
else {
if (idle_spawn_rate >= 8) {
"server seems busy, (you may need "
"to increase StartServers, or Min/MaxSpareServers), "
"spawning %d children, there are %d idle, and "
"%d total children", idle_spawn_rate,
}
for (i = 0; i < free_length; ++i) {
#ifdef TPF
if(free_length == 1) {
shutdown_pending = 1;
"No active child processes: shutting down");
}
}
#else
#endif /* TPF */
}
/* the next time around we want to spawn twice as many if this
* wasn't good enough, but not if we've just done a graceful
*/
}
else if (idle_spawn_rate < MAX_SPAWN_RATE) {
idle_spawn_rate *= 2;
}
}
}
else {
idle_spawn_rate = 1;
}
}
/*****************************************************************
* Executive routines.
*/
{
int index;
ap_server_conf = s;
/* XXX: hey, what's the right way for the mpm to indicate a fatal error? */
"no listening sockets available, shutting down");
return 1;
}
"Could not open pipe-of-death.");
return 1;
}
if (!is_graceful) {
}
#ifdef SCOREBOARD_FILE
else {
}
#endif
set_signals();
/* If we're doing a graceful_restart then we're going to see a lot
* of children exiting immediately when we get into the main loop
* below (because we just sent them AP_SIG_GRACEFUL). This happens pretty
* rapidly... and for each one that exits we'll start a new one until
* we reach at least daemons_min_free. But we may be permitted to
* start more than that, so we'll just keep track of how many we're
* supposed to start up without the 1 second penalty between each fork.
*/
}
if (!is_graceful) {
}
else {
/* give the system some time to recover before kicking into
* exponential mode */
}
"%s configured -- resuming normal operations",
"Server built: %s", ap_get_server_built());
restart_pending = shutdown_pending = 0;
while (!restart_pending && !shutdown_pending) {
int child_slot;
int status;
/* this is a memory leak, but I'll fix it later. */
/* XXX: if it takes longer than 1 second for all our children
* to start up and get into IDLE state then we may spawn an
* extra child
*/
/* non-fatal death... note that it's gone in the scoreboard. */
if (child_slot >= 0) {
(request_rec *) NULL);
&& child_slot < ap_daemons_limit) {
/* we're still doing a 1-for-1 replacement of dead
* children with new children
*/
}
}
/* handled */
#endif
}
else if (is_graceful) {
/* Great, we've probably just lost a slot in the
* scoreboard. Somehow we don't know about this
* child.
*/
0, ap_server_conf,
}
/* Don't perform idle maintenance when a child dies,
* only do it when there's a timeout. Remember only a
* finite number of children can die, and it's pretty
* pathological for a lot to die suddenly.
*/
continue;
}
else if (remaining_children_to_start) {
/* we hit a 1 second timeout in which none of the previous
* generation of children needed to be reaped... so assume
* they're all done, and pick up the slack if any is left.
*/
/* In any event we really shouldn't do the code below because
* few of the servers we just started are in the IDLE state
* yet, so we'd mistakenly create an extra server.
*/
continue;
}
#ifdef TPF
sleep(1);
#endif /*TPF */
}
if (shutdown_pending) {
/* Time to gracefully shut down:
* Kill child processes, tell them to call child_exit, etc...
*/
}
/* cleanup pid file on normal shutdown */
{
0, ap_server_conf,
"removed PID file %s (pid=%ld)",
}
"caught SIGTERM, shutting down");
return 1;
}
/* we've been told to restart */
if (one_process) {
/* not worth thinking about */
return 1;
}
/* advance to the next generation */
/* XXX: we really need to make sure this new generation number isn't in
* use by any of the children.
*/
if (is_graceful) {
"Graceful restart requested, doing restart");
/* kill off the idle ones */
#ifndef SCOREBOARD_FILE
/* This is mostly for debugging... so that we know what is still
* gracefully dealing with existing request. But we can't really
* do it if we're in a SCOREBOARD_FILE because it'll cause
* corruption too easily.
*/
}
}
#endif
}
else {
/* Kill 'em off */
}
ap_reclaim_child_processes(0); /* Not when just starting up */
"SIGHUP received. Attempting to restart");
}
return 0;
}
{
static int restart_num = 0;
if (debug)
else
{
}
/* sigh, want this only the second time around */
if (restart_num++ == 1) {
is_graceful = 0;
if (!one_process && !no_detach) {
}
}
ap_extended_status = 0;
}
static void prefork_hooks(apr_pool_t *p)
{
#ifdef AUX3
(void) set42sig();
#endif
}
{
return err;
}
return NULL;
}
{
return err;
}
if (ap_daemons_min_free <= 0) {
"WARNING: detected MinSpareServers set to non-positive.");
"Resetting to 1 to avoid almost certain Apache failure.");
"Please read the documentation.");
ap_daemons_min_free = 1;
}
return NULL;
}
{
return err;
}
return NULL;
}
{
return err;
}
if (ap_daemons_limit > HARD_SERVER_LIMIT) {
"WARNING: MaxClients of %d exceeds compile time limit "
" lowering MaxClients to %d. To increase, please "
"see the", HARD_SERVER_LIMIT);
" HARD_SERVER_LIMIT define in %s.",
}
else if (ap_daemons_limit < 1) {
"WARNING: Require MaxClients > 0, setting to 1");
ap_daemons_limit = 1;
}
return NULL;
}
static const command_rec prefork_cmds[] = {
"Number of child processes launched at server startup"),
"Minimum number of idle children, to handle request spikes"),
"Maximum number of idle children"),
"Maximum number of children alive at the same time"),
{ NULL }
};
NULL, /* hook to run before apache parses args */
NULL, /* create per-directory config structure */
NULL, /* merge per-directory config structures */
NULL, /* create per-server config structure */
NULL, /* merge per-server config structures */
prefork_cmds, /* command apr_table_t */
prefork_hooks, /* register hooks */
};