Bug 26142 - EnableSendFile Off for Windows XP Home
Summary: EnableSendFile Off for Windows XP Home
Alias: None
Product: Apache httpd-2
Classification: Unclassified
Component: Runtime Config (show other bugs)
Version: 2.2.3
Hardware: Other Windows XP
: P3 major with 3 votes (vote)
Target Milestone: ---
Assignee: Apache HTTPD Bugs Mailing List
Keywords: MassUpdate
: 36264 (view as bug list)
Depends on:
Reported: 2004-01-14 20:14 UTC by Aaron West
Modified: 2018-11-07 21:09 UTC (History)
2 users (show)


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Description Aaron West 2004-01-14 20:14:14 UTC
I've seen this problem on 2.0.47 and 2.0.48 for win32, on Windows XP Home. 
EnableSendFile Off is needed on my system. Otherwise, long pages get truncated.

To reproduce, try this documentation page from a local apache 2.0.48 install 
on Windows XP (Home):

Or try this URL specified above to see the problem, but note that you'll be 
connecting through a wireless router to a DHCP address on my laptop, to a 
service that I've started manually, so don't count on it to be running. Email 
me if it's not, and you want to see it.

The amount of data output from the page depends on the connection speed. I'm 
seeing much less data through my wireless connection than I saw through 
localhost. This problem seems to affect all "/manual" URLs. 

Component:Core is merely a guess.

Example error:

[Wed Jan 14 11:31:53 2004] [info] (OS 996)Overlapped I/O event is not in a 
signaled state.  : core_output_filter: writing data to the network

This page seems to be relevant:


If you could make the win32 installs default to EnableSendFile Off, that might 
be a better default.

Build info:

md5 and gpg tests were performed on 2.0.48.
C:\src\apache>md5sum httpd-2.0.48-win32-src.zip
9540125bd43ffe05749c91c93f6dd643 *httpd-2.0.48-win32-src.zip

I built apache myself with Visual C++ 6.0 SP3 using nmake /f Makefile.win:

Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 12.00.8804 for 80x86


Microsoft (R) Program Maintenance Utility   Version 6.00.8168.0

awk from cygwin:
C:\src\apache\HTTPD-~1.48>awk --version
GNU Awk 3.1.3
Comment 1 Joshua Slive 2004-01-14 20:28:00 UTC
I don't know anything about this specific bug, but I support setting
EnableSendfile off
by default on all platforms.

There are two many obscure causes of sendfile failures.  And almost all of them
result in either no error log message, or a very-difficult-to-decipher message.
Comment 2 William A. Rowe Jr. 2004-01-16 05:30:15 UTC
  Sendfile Off will not become a default setting - Apache is created and
  maintained mostly for server hardware, we don't tweak the universal examples
  for non-server installations.

  It would be possible however to disable sendfile on XP Home installations
  using the installer.  I'll investigate that reasonable suggestion, with
  the httpd-win32-msi packaging instead of the default config files.
Comment 3 Joshua Slive 2004-01-16 17:34:33 UTC
As I said, I'm not focusing specifically on the problem reported here.

Sendfile causes numerous hard-to-debug problems on unix and windows.
One of them is here:
but I have seen several others on the users list.
Comment 4 Aaron West 2004-02-02 07:36:16 UTC
I suggest just adding a comment in httpd.conf as follows:

# Note: Static content will be truncated or not displayed if SendFile 
# does not work on your OS. OS's known to not support SendFile include:
# Windows XP Home, ...

I *did* review httpd.conf before using my installation of Apache, and surely 
would have noticed that.
Comment 5 Paul Querna 2004-08-30 04:47:38 UTC
Is it possible to setup the windows installer to prompt users about this issue and/or set it to off by 
default for XP home?

Comment 6 Nick Kew 2005-08-19 02:00:28 UTC
*** Bug 36264 has been marked as a duplicate of this bug. ***
Comment 7 Simeon Albertson 2006-11-05 10:47:34 UTC
It is highly possible that this bug is caused by too low free space ratio on the
hard drive htdocs and/or Apache is installed to. This was applied to me on
Windows XP Pro running Apache 2.2.3 with only the mod_authz_host module loaded.
Therefore it should by definition be a core bug or in the extreme a bug in this
single module.

If the Apache team has any questions regarding this bug, contact me by mail:
Comment 8 William A. Rowe Jr. 2007-12-21 20:49:02 UTC
"set it to off by default for XP home?"

why not universally off, and let them toggle it.

Seems like extra/httpd-mpm under winnt_mpm is the right place for this.
Comment 9 William A. Rowe Jr. 2009-05-19 23:54:14 UTC
Here's an even stranger reason we must change this;


"Workstation and client versions of Windows optimize the TransmitFile function for minimum memory and resource utilization by limiting the number of concurrent TransmitFile operations allowed on the system to a maximum of two. On Windows Vista, Windows XP, Windows 2000 Professional, and Windows NT Workstation 3.51 and later only two outstanding TransmitFile requests are handled simultaneously; the third request will wait until one of the previous requests is completed."

How's that for useless?
Comment 10 William A. Rowe Jr. 2018-11-07 21:09:58 UTC
Please help us to refine our list of open and current defects; this is a mass update of old and inactive Bugzilla reports which reflect user error, already resolved defects, and still-existing defects in httpd.

As repeatedly announced, the Apache HTTP Server Project has discontinued all development and patch review of the 2.2.x series of releases. The final release 2.2.34 was published in July 2017, and no further evaluation of bug reports or security risks will be considered or published for 2.2.x releases. All reports older than 2.4.x have been updated to status RESOLVED/LATER; no further action is expected unless the report still applies to a current version of httpd.

If your report represented a question or confusion about how to use an httpd feature, an unexpected server behavior, problems building or installing httpd, or working with an external component (a third party module, browser etc.) we ask you to start by bringing your question to the User Support and Discussion mailing list, see [https://httpd.apache.org/lists.html#http-users] for details. Include a link to this Bugzilla report for completeness with your question.

If your report was clearly a defect in httpd or a feature request, we ask that you retest using a modern httpd release (2.4.33 or later) released in the past year. If it can be reproduced, please reopen this bug and change the Version field above to the httpd version you have reconfirmed with.

Your help in identifying defects or enhancements still applicable to the current httpd server software release is greatly appreciated.