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Posted to cvs@httpd.apache.org by mr...@apache.org on 2020/01/30 20:07:27 UTC
svn commit: r1873381 - in /httpd/httpd/branches/2.4.x/docs/manual/mod:
event.xml mpm_common.xml
Author: mrumph
Date: Thu Jan 30 20:07:26 2020
New Revision: 1873381
URL: http://svn.apache.org/viewvc?rev=1873381&view=rev
Log:
Fix some grammar errors in the docs
Modified:
httpd/httpd/branches/2.4.x/docs/manual/mod/event.xml
httpd/httpd/branches/2.4.x/docs/manual/mod/mpm_common.xml
Modified: httpd/httpd/branches/2.4.x/docs/manual/mod/event.xml
URL: http://svn.apache.org/viewvc/httpd/httpd/branches/2.4.x/docs/manual/mod/event.xml?rev=1873381&r1=1873380&r2=1873381&view=diff
==============================================================================
--- httpd/httpd/branches/2.4.x/docs/manual/mod/event.xml (original)
+++ httpd/httpd/branches/2.4.x/docs/manual/mod/event.xml Thu Jan 30 20:07:26 2020
@@ -80,24 +80,29 @@ of the <directive>AsyncRequestWorkerFact
The status page of <module>mod_status</module> shows new columns under the Async connections section:</p>
<dl>
<dt>Writing</dt>
- <dd>While sending the response to the client, it might happen that the TCP write buffer fills up because the connection is too slow. Usually in this case a <code>write()</code> to the socket returns <code>EWOULDBLOCK</code> or <code>EAGAIN</code>, to become writable again after an idle time. The worker holding the socket might be able to offload the waiting task to the listener thread, that in turn will re-assign it to the first idle worker thread available once an event will be raised for the socket (for example, "the socket is now writable"). Please check the Limitations section for more information.
+ <dd>While sending the response to the client, it might happen that the TCP write buffer fills up because the connection is too slow.
+ Usually in this case, a <code>write()</code> to the socket returns <code>EWOULDBLOCK</code> or <code>EAGAIN</code> to become writable again after an idle time.
+ The worker holding the socket might be able to offload the waiting task to the listener thread, that in turn will re-assign it to the first idle worker thread available once an event will be raised for the socket (for example, "the socket is now writable").
+ Please check the Limitations section for more information.
</dd>
<dt>Keep-alive</dt>
<dd>Keep Alive handling is the most basic improvement from the worker MPM.
Once a worker thread finishes to flush the response to the client, it can offload the
- socket handling to the listener thread, that in turns will wait for any event from the
+ socket handling to the listener thread, that in turn will wait for any event from the
OS, like "the socket is readable". If any new request comes from the client, then the
listener will forward it to the first worker thread available. Conversely, if the
<directive module="core">KeepAliveTimeout</directive> occurs then the socket will be
- closed by the listener. In this way the worker threads are not responsible for idle
- sockets and they can be re-used to serve other requests.</dd>
+ closed by the listener. In this way, the worker threads are not responsible for idle
+ sockets, and they can be re-used to serve other requests.</dd>
<dt>Closing</dt>
<dd>Sometimes the MPM needs to perform a lingering close, namely sending back an early error to the client while it is still transmitting data to httpd.
Sending the response and then closing the connection immediately is not the correct thing to do since the client (still trying to send the rest of the
- request) would get a connection reset and could not read the httpd's response. The lingering close is time bounded but it can take relatively long
- time, so it's offloaded to a worker thread (including the shutdown hooks and real socket close). From 2.4.28 onward this is also the
+ request) would get a connection reset and could not read the httpd's response.
+ The lingering close is time-bounded, but it can take a relatively long
+ time, so it's offloaded to a worker thread (including the shutdown hooks and real socket close).
+ From 2.4.28 onward, this is also the
case when connections finally timeout (the listener thread never handles connections besides waiting for and dispatching their events).
</dd>
</dl>
@@ -107,33 +112,33 @@ of the <directive>AsyncRequestWorkerFact
</section>
<section id="graceful-close"><title>Graceful process termination and Scoreboard usage</title>
- <p>This mpm showed some scalability bottlenecks in the past leading to the following
+ <p>This mpm showed some scalability bottlenecks in the past, leading to the following
error: "<strong>scoreboard is full, not at MaxRequestWorkers</strong>".
<directive module="mpm_common">MaxRequestWorkers</directive>
limits the number of simultaneous requests that will be served at any given time
and also the number of allowed processes
(<directive module="mpm_common">MaxRequestWorkers</directive>
- / <directive module="mpm_common">ThreadsPerChild</directive>), meanwhile
+ / <directive module="mpm_common">ThreadsPerChild</directive>); meanwhile,
the Scoreboard is a representation of all the running processes and
the status of their worker threads. If the scoreboard is full (so all the
threads have a state that is not idle) but the number of active requests
served is not <directive module="mpm_common">MaxRequestWorkers</directive>,
it means that some of them are blocking new requests that could be served
but that are queued instead (up to the limit imposed by
- <directive module="mpm_common">ListenBacklog</directive>). Most of the times
+ <directive module="mpm_common">ListenBacklog</directive>). Most of the time,
the threads are stuck in the Graceful state, namely they are waiting to
finish their work with a TCP connection to safely terminate and free up a
- scoreboard slot (for example handling long running requests, slow clients
+ scoreboard slot (for example, handling long-running requests, slow clients
or connections with keep-alive enabled). Two scenarios are very common:</p>
<ul>
- <li>During a <a href="../stopping.html#graceful">graceful restart</a>.
- The parent process signals all its children to complete
+ <li>During a <a href="../stopping.html#graceful">graceful restart</a>,
+ the parent process signals all its children to complete
their work and terminate, while it reloads the config and forks new
processes. If the old children keep running for a while before stopping,
the scoreboard will be partially occupied until their slots are freed.
</li>
- <li>When the server load goes down in a way that causes httpd to
- stop some processes (for example due to
+ <li>The server load goes down in a way that causes httpd to
+ stop some processes (for example, due to
<directive module="mpm_common">MaxSpareThreads</directive>).
This is particularly problematic because when the load increases again,
httpd will try to start new processes.
@@ -149,7 +154,7 @@ of the <directive>AsyncRequestWorkerFact
<directive module="mpm_common">ServerLimit</directive>.
<directive module="mpm_common">MaxRequestWorkers</directive> and
<directive module="mpm_common">ThreadsPerChild</directive> are used
- to limit the amount of active processes, meanwhile
+ to limit the amount of active processes; meanwhile,
<directive module="mpm_common">ServerLimit</directive>
takes also into account the ones doing a graceful
close to allow extra slots when needed. The idea is to use
@@ -162,7 +167,7 @@ of the <directive>AsyncRequestWorkerFact
<li>During graceful shutdown, if there are more running worker threads
than open connections for a given process, terminate these threads to
free resources faster (which may be needed for new processes).</li>
- <li>If the scoreboard is full, prevent more processes to finish
+ <li>If the scoreboard is full, prevent more processes from finishing
gracefully due to reduced load until old processes have terminated
(otherwise the situation would get worse once the load increases again).</li>
</ul>
@@ -186,14 +191,14 @@ of the <directive>AsyncRequestWorkerFact
data, and the amount of data produced by the filter is too big to be
buffered in memory, the thread used for the request is not freed while
httpd waits until the pending data is sent to the client.<br />
- To illustrate this point we can think about the following two situations:
+ To illustrate this point, we can think about the following two situations:
serving a static asset (like a CSS file) versus serving content retrieved from
FCGI/CGI or a proxied server. The former is predictable, namely the event MPM
has full visibility on the end of the content and it can use events: the worker
thread serving the response content can flush the first bytes until <code>EWOULDBLOCK</code>
or <code>EAGAIN</code> is returned, delegating the rest to the listener. This one in turn
- waits for an event on the socket, and delegates the work to flush the rest of the content
- to the first idle worker thread. Meanwhile in the latter example (FCGI/CGI/proxied content)
+ waits for an event on the socket and delegates the work to flush the rest of the content
+ to the first idle worker thread. Meanwhile in the latter example (FCGI/CGI/proxied content),
the MPM can't predict the end of the response and a worker thread has to finish its work
before returning the control to the listener. The only alternative is to buffer the
response in memory, but it wouldn't be the safest option for the sake of the
@@ -211,7 +216,7 @@ of the <directive>AsyncRequestWorkerFact
</ul>
<p>Before these new APIs where made available, the traditional <code>select</code> and <code>poll</code> APIs had to be used.
Those APIs get slow if used to handle many connections or if the set of connections rate of change is high.
- The new APIs allow to monitor much more connections and they perform way better when the set of connections to monitor changes frequently. So these APIs made it possible to write the event MPM, that scales much better with the typical HTTP pattern of many idle connections.</p>
+ The new APIs allow to monitor many more connections, and they perform way better when the set of connections to monitor changes frequently. So these APIs made it possible to write the event MPM, that scales much better with the typical HTTP pattern of many idle connections.</p>
<p>The MPM assumes that the underlying <code>apr_pollset</code>
implementation is reasonably threadsafe. This enables the MPM to
@@ -241,7 +246,7 @@ of the <directive>AsyncRequestWorkerFact
<ul>
<li>To use this MPM on FreeBSD, FreeBSD 5.3 or higher is recommended.
- However, it is possible to run this MPM on FreeBSD 5.2.1, if you
+ However, it is possible to run this MPM on FreeBSD 5.2.1 if you
use <code>libkse</code> (see <code>man libmap.conf</code>).</li>
<li>For NetBSD, at least version 2.0 is recommended.</li>
@@ -310,9 +315,9 @@ of the <directive>AsyncRequestWorkerFact
<p>To mitigate this problem, the event MPM does two things:</p>
<ul>
- <li>it limits the number of connections accepted per process, depending on the
+ <li>It limits the number of connections accepted per process, depending on the
number of idle request workers;</li>
- <li>if all workers are busy, it will
+ <li>If all workers are busy, it will
close connections in keep-alive state even if the keep-alive timeout has
not expired. This allows the respective clients to reconnect to a
different process which may still have worker threads available.</li>
Modified: httpd/httpd/branches/2.4.x/docs/manual/mod/mpm_common.xml
URL: http://svn.apache.org/viewvc/httpd/httpd/branches/2.4.x/docs/manual/mod/mpm_common.xml?rev=1873381&r1=1873380&r2=1873381&view=diff
==============================================================================
--- httpd/httpd/branches/2.4.x/docs/manual/mod/mpm_common.xml (original)
+++ httpd/httpd/branches/2.4.x/docs/manual/mod/mpm_common.xml Thu Jan 30 20:07:26 2020
@@ -150,7 +150,7 @@ of the daemon</description>
<usage>
<p>The <directive>PidFile</directive> directive sets the file to
which the server records the process id of the daemon. If the
- filename is not absolute then it is assumed to be relative to the
+ filename is not absolute, then it is assumed to be relative to the
<directive module="core">ServerRoot</directive>.</p>
<example><title>Example</title>
@@ -350,8 +350,8 @@ in *BSDs.</compatibility>
<usage>
<p>The maximum length of the queue of pending connections.
- Generally no tuning is needed or desired, however on some
- systems it is desirable to increase this when under a TCP SYN
+ Generally no tuning is needed or desired; however on some
+ systems, it is desirable to increase this when under a TCP SYN
flood attack. See the backlog parameter to the
<code>listen(2)</code> system call.</p>
@@ -390,9 +390,9 @@ simultaneously</description>
<directive module="mpm_common">ServerLimit</directive>.</p>
<p>For threaded and hybrid servers (<em>e.g.</em> <module>event</module>
- or <module>worker</module>) <directive>MaxRequestWorkers</directive> restricts
+ or <module>worker</module>), <directive>MaxRequestWorkers</directive> restricts
the total number of threads that will be available to serve clients.
- For hybrid MPMs the default value is <code>16</code> (<directive
+ For hybrid MPMs, the default value is <code>16</code> (<directive
module="mpm_common">ServerLimit</directive>) multiplied by the value of
<code>25</code> (<directive module="mpm_common"
>ThreadsPerChild</directive>). Therefore, to increase <directive
@@ -450,7 +450,7 @@ will handle during its life</description
<code>0</code>, then the process will never expire.</p>
<p>Setting <directive>MaxConnectionsPerChild</directive> to a
- non-zero value limits the amount of memory that process can consume
+ non-zero value limits the amount of memory that a process can consume
by (accidental) memory leakage.</p>
</usage>
</directivesynopsis>
@@ -472,7 +472,7 @@ will handle during its life</description
<p>For <module>worker</module> and <module>event</module>, the default is
<code>MaxSpareThreads 250</code>. These MPMs deal with idle threads
on a server-wide basis. If there are too many idle threads in the
- server then child processes are killed until the number of idle
+ server, then child processes are killed until the number of idle
threads is less than this number. Additional processes/threads
might be created if <directive module="mpm_common">ListenCoresBucketsRatio</directive>
is enabled.</p>
@@ -522,7 +522,7 @@ spikes</description>
<p><module>worker</module> and <module>event</module> use a default of
<code>MinSpareThreads 75</code> and deal with idle threads on a server-wide
- basis. If there aren't enough idle threads in the server then child
+ basis. If there aren't enough idle threads in the server, then child
processes are created until the number of idle threads is greater
than <var>number</var>. Additional processes/threads
might be created if <directive module="mpm_common">ListenCoresBucketsRatio</directive>
@@ -530,7 +530,7 @@ spikes</description>
<p><module>mpm_netware</module> uses a default of
<code>MinSpareThreads 10</code> and, since it is a single-process
- MPM, tracks this on a server-wide bases.</p>
+ MPM, tracks this on a server-wide basis.</p>
<p><module>mpmt_os2</module> works
similar to <module>mpm_netware</module>. For
@@ -570,7 +570,7 @@ the child processes</description>
<p>File-based shared memory is useful for third-party applications
that require direct access to the scoreboard.</p>
- <p>If you use a <directive>ScoreBoardFile</directive> then
+ <p>If you use a <directive>ScoreBoardFile</directive>, then
you may see improved speed by placing it on a RAM disk. But be
careful that you heed the same warnings about log file placement
and <a href="../misc/security_tips.html">security</a>.</p>
@@ -869,7 +869,7 @@ client connections</description>
will be achievable if <directive>ThreadStackSize</directive> is
set to a value lower than the operating system default. This type
of adjustment should only be made in a test environment which allows
- the full set of web server processing can be exercised, as there
+ the full set of web server processing to be exercised, as there
may be infrequent requests which require more stack to process.
The minimum required stack size strongly depends on the modules
used, but any change in the web server configuration can invalidate