Commenting out all BalancerMember http://... let apache run again, and I can see than the Load Balancer Manager page. Clicking on the balancer://mycluster link (http://localhost/balancer-manager?b=mycluster) crashes the connection, but apache keeps running.

in the windows event log
Protokollname: Application
Quelle:        Application Error
Datum:         01.01.2012 18:58:15
Ereignis-ID:   1000
Aufgabenkategorie:(100)
Ebene:         Fehler
Schlüsselwörter:Klassisch
Benutzer:      Nicht zutreffend
Computer:      zengarden
Beschreibung:
Name der fehlerhaften Anwendung: httpd.exe, Version: 2.3.16.0, Zeitstempel: 0x4eebe6cb
Name des fehlerhaften Moduls: mod_proxy_balancer.so, Version: 2.3.16.0, Zeitstempel: 0x4eebe6a6
Ausnahmecode: 0xc0000005
Fehleroffset: 0x0000000000002db0
ID des fehlerhaften Prozesses: 0x86c
Startzeit der fehlerhaften Anwendung: 0x01ccc8aee7051bb9
Pfad der fehlerhaften Anwendung: C:\Apache23\bin\httpd.exe
Pfad des fehlerhaften Moduls: C:\Apache23\modules\mod_proxy_balancer.so
Berichtskennung: 2d7508eb-34a2-11e1-90ed-f0def11c30f7
Ereignis-XML:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
  <System>
    <Provider Name="Application Error" />
    <EventID Qualifiers="0">1000</EventID>
    <Level>2</Level>
    <Task>100</Task>
    <Keywords>0x80000000000000</Keywords>
    <TimeCreated SystemTime="2012-01-01T17:58:15.000000000Z" />
    <EventRecordID>1259</EventRecordID>
    <Channel>Application</Channel>
    <Computer>zengarden</Computer>
    <Security />
  </System>
  <EventData>
    <Data>httpd.exe</Data>
    <Data>2.3.16.0</Data>
    <Data>4eebe6cb</Data>
    <Data>mod_proxy_balancer.so</Data>
    <Data>2.3.16.0</Data>
    <Data>4eebe6a6</Data>
    <Data>c0000005</Data>
    <Data>0000000000002db0</Data>
    <Data>86c</Data>
    <Data>01ccc8aee7051bb9</Data>
    <Data>C:\Apache23\bin\httpd.exe</Data>
    <Data>C:\Apache23\modules\mod_proxy_balancer.so</Data>
    <Data>2d7508eb-34a2-11e1-90ed-f0def11c30f7</Data>
  </EventData>
</Event>

This isn't a crash, but rather a configuration error:

[Fri Dec 30 20:55:43.004798 2011] [proxy_balancer:emerg] [pid 3632:tid 428]
(22)Invalid argument: AH01186: worker slotmem_grab failed
AH00020: Configuration Failed

Hmm, I remember I once wrote experimental module that used provider logic and it crashed on windows. Think this has to do something with dso logic and which pool has been used. Let me see if I can find that code and see how I fixed that. Might be this is the same cause.

Just saying it is a crash. The pid file still exist. Also there is a popup from windows telling me there is a crash and there is the event log entry.

OK, so the reason is mod_slotmem_shm

I added some debugging and the reason is that win32 calls config twice.
That cause mod_slotmem_shm to try to allocate shared storage twice, and
the second avocation fails because it already reached limit in first call.

Fixed both in the trunk and 2.4.x
Could you check if r1240170 fixes the issue on your side?

Now lbmethod_bybusyness_module nor lbmethod_byrequests_module nor lbmethod_bytraffic_module. No issue while building.
Without that modules I get

C:\Apache2x\bin>httpd -S
AH00526: Syntax error on line 209 of C:/Apache2x/conf/httpd.conf:
BalancerMember Can't find 'byrequests' lb method

Than I tried to load each module single, but they don't load at all.

C:\Apache2x\bin>httpd -S
httpd: Syntax error on line 121 of C:/Apache2x/conf/httpd.conf: Cannot load C:/Apache2x/mod_lbmethod_bybusyness.so into server: Das angegebene Modul wurde
nicht gefunden.


C:\Apache2x\bin>httpd -S
httpd: Syntax error on line 122 of C:/Apache2x/conf/httpd.conf: Cannot load C:/Apache2x/mod_lbmethod_byrequests.so into server: Das angegebene Modul wurde
nicht gefunden.


C:\Apache2x\bin>httpd -S
httpd: Syntax error on line 123 of C:/Apache2x/conf/httpd.conf: Cannot load C:/Apache2x/mod_lbmethod_bytraffic.so into server: Das angegebene Modul wurde n
icht gefunden.



Positive I can say that the module itself now load without apache crashing

(In reply to comment #7)
> Now lbmethod_bybusyness_module nor lbmethod_byrequests_module nor
> lbmethod_bytraffic_module. No issue while building.
> Without that modules I get
> 
> C:\Apache2x\bin>httpd -S
> AH00526: Syntax error on line 209 of C:/Apache2x/conf/httpd.conf:
> BalancerMember Can't find 'byrequests' lb method

It is expected, that using method "byrequests" without having lbmethod_byrequests_module does not work.

> Than I tried to load each module single, but they don't load at all.
> 
> C:\Apache2x\bin>httpd -S
> httpd: Syntax error on line 121 of C:/Apache2x/conf/httpd.conf: Cannot load
> C:/Apache2x/mod_lbmethod_bybusyness.so into server: Das angegebene Modul wurde
> nicht gefunden.

> C:\Apache2x\bin>httpd -S
> httpd: Syntax error on line 122 of C:/Apache2x/conf/httpd.conf: Cannot load
> C:/Apache2x/mod_lbmethod_byrequests.so into server: Das angegebene Modul wurde
> nicht gefunden.
> 
> C:\Apache2x\bin>httpd -S
> httpd: Syntax error on line 123 of C:/Apache2x/conf/httpd.conf: Cannot load
> C:/Apache2x/mod_lbmethod_bytraffic.so into server: Das angegebene Modul wurde n
> icht gefunden.

Fpr non-Germans "The given module has not been found".

Mario: did you notice the strange path? Modules usually go to a "modules" directory. It seems your httpd.conf doesn't have the LoadModule lines correct. Can you please double check, how the LoadModule lines for those modules look like, and whether the installed modules files actually are in the correct directories?

Regards,

Rainer

I'm to blame on this. I see the problem in installwinconf.awk. 

Fixed Trunk: r1243404
2.4: r1243405

Works on non localhost. Thanks for the hint with the paths and the fix svn.
With external servers works fine now. 

With the original setup on only localhost I have now

--- snip ---
Bad Request

Your browser sent a request that this server could not understand.
Size of a request header field exceeds server limit.

X-Forwarded-Server
--- /snip ---

I changed 

LimitRequestFields      0
LimitRequestFieldsize	12392

But than I get 
[Mon Feb 13 11:38:37.294511 2012] [proxy_balancer:emerg] [pid 9324:tid 376] (22)Invalid argument: AH01186: worker slotmem_grab failed
[Mon Feb 13 11:38:37.295511 2012] [:emerg] [pid 9324:tid 376] AH00020: Configuration Failed, exiting
[Mon Feb 13 11:38:37.308512 2012] [mpm_winnt:crit] [pid 5980:tid 528] AH00419: master_main: create child process failed. Exiting.
[Mon Feb 13 11:38:38.202563 2012] [mpm_winnt:notice] [pid 9712:tid 452] AH00364: Child: All worker threads have exited.

With apache 2.4.1 it works if I change the balancer root to /test

e.g.
ProxyPass /test/ balancer://mycluster
ProxyPassReverse /test/ balancer://mycluster

Having the the old way 
ProxyPass / balancer://mycluster
ProxyPassReverse / balancer://mycluster

I get a 502. Any idea how to fix this?

Unable to start the apache webserver (httpd). Getting terminated in between.
How to start the webserver?

Linux: Ubuntu 11.10 i386 x32 bit
Apache2: 2.4.1

Apache2 source got compiled and installed, when try to start, failed due to:

[proxy_balancer:emerg] [pid 2325] AH01177: Failed to lookup provider 'shm' for 'slotmem': is mod_slotmem_shm loaded??
[:emerg] [pid 2325] AH00020: Configuration Failed, exiting

Results on running: 
./httpd -S

VirtualHost configuration:
ServerRoot: "/usr/local/apache-2.4.1"
Main DocumentRoot: "/usr/local/apache-2.4.1/htdocs"
Main ErrorLog: "/usr/local/apache-2.4.1/logs/error_log"
Mutex default: dir="/usr/local/apache-2.4.1/logs" mechanism=default
Mutex mpm-accept: using_defaults
Mutex proxy-balancer-shm: using_defaults
PidFile: "/usr/local/apache-2.4.1/logs/httpd.pid"
Define: DUMP_VHOSTS
Define: DUMP_RUN_CFG
User: name="daemon" id=1
Group: name="daemon" id=1

error_log:
[proxy_balancer:emerg] [pid 2705] AH01177: Failed to lookup provider 'shm' for 'slotmem': is mod_slotmem_shm loaded??
[:emerg] [pid 2705] AH00020: Configuration Failed, exiting

Server is runnable, upon compiling without --enable-proxy --enable-proxy-balancer --enable-proxy-http options.

Got it, this is no issue with proxy enabled option.
Its basically required to enable the corresponding required module!

[proxy_balancer:emerg] [pid 29584] AH01177: Failed to lookup provider 'shm' for 'slotmem': is mod_slotmem_shm loaded??

by uncommenting the below entry, server has ran without any issue by using 2.4.1 without any additional patches.

LoadModule slotmem_shm_module modules/mod_slotmem_shm.so

msubbareddy: don't hijack,much less close, existing bug reports opened by other users.

It looks like each balancer creates the SHM for its number of workers (1
in my case) using its unique ->sname. After that, each worker grabs a
slot from this.

I have several virtual hosts pointing to the same balancer (by rewrite
[P]). So, the second time, the balancer calls shm's slotmem_create again
with its name, that already exists -> kind-of noop.

Now, the SHM under the balancer's name has still only 1 slot (that is
already occupied).

When the worker now wants to (re-)grab its slot, I get:

[slotmem_shm:debug] mod_slotmem_shm.c(575): AH02293: slotmem(...) grab
failed. Num 1/num_free 0 [proxy_balancer:emerg] (22)Invalid argument:
AH01186: worker slotmem_grab failed

Does anybody know the intention behind this?

I also encounter such issue. The virtual hosts configuration is as below:

<VirtualHost *:80>
   ServerAdmin webmaster@www.mydomain.sites
   ServerName www.mydomain.sites
   ProxyPass /google http://www.google.com/
   ErrorLog "logs/www.mydomain.sites-error_log"
   CustomLog "logs/www.mydomain.sites-access_log" common
</VirtualHost>
<Proxy balancer://testBalancer>
BalancerMember http://www.app03.v2/
BalancerMember http://www.app03.v22/
</Proxy>

Linux: Ubuntu 10.10 i686 x32 bit
Apache2: 2.4.1

By above configuration, it crash apache during start.
error log:
[proxy_balancer:emerg] [pid 11746:tid 3077961472] (22)Invalid argument: AH01186: worker slotmem_grab failed


Any help is appreciated.

All,

I had similar error when the balancer included outside from Virtual host, for testing I did include the balancer file inside the virtual host and it did work and nolonger getting the error.



<VirtualHost abc.com:80>

Include conf/abc.com.conf

Include conf/balancer_ab.conf
Include conf/balancer_xyz.conf

</VirtualHost>

This issue still isn't fixed.

What about applying the patch proposed on the mailinglist some time ago?
http://mail-archives.apache.org/mod_mbox/httpd-dev/201204.mbox/%3C1334306253.1695.50.camel%40florian-desktop%3E

I also stumbled across this issue today in httpd-2.4.2...

See http://www.mail-archive.com/dev%40httpd.apache.org/msg54912.html

Just tested the patch against my httpd-2.4.2 installation and it resolves the issue.

Patch:
http://mail-archives.apache.org/mod_mbox/httpd-dev/201204.mbox/%3C1334306253.1695.50.camel%40florian-desktop%3E


Maybe some commiter can have a look on this?

Created attachment 28934 [details]
proposed patch for httpd-2.4.2

The patch works for me, too!

The nice folks over at Apache Lounge built the patched module for me ( http://www.apachelounge.com/viewtopic.php?t=4805 ) but the error persists:

[proxy_balancer:emerg] [pid 6496:tid 620] (22)Invalid argument: AH01186: worker slotmem_grab failed

Does anything obvious appear wrong with my configuration?

<VirtualHost _default_:9000> 

  ProxyTimeout 900 
  SSLProxyEngine On 
  ProxyPreserveHost On 

  <Proxy balancer://my_cluster> 
    BalancerMember https://paz:9000 route=nA 
    BalancerMember https://baz:9000 route=nB 
    ProxySet lbmethod=byrequests stickysession=FOO_STICKY nofailover=Off 
  </Proxy> 

  ProxyPass /foo/   balancer://my_cluster/foo/ 
  Header add Set-Cookie "FOO_STICKY=s.%{BALANCER_WORKER_ROUTE}e;path=/;secure" env=BALANCER_ROUTE_CHANGED 

</VirtualHost>

This seems to be still present in Apache 2.4.3.
Is there any news on this issue?
What can I do to help resolving this issue?

Trunk handles this differently and that code path is projected to be backported. Can you check that trunk works for you?

Jim, I haven't tested yet with trunk. But do you know which commit fixed the issue in trunk?

(In reply to comment #27)
> Trunk handles this differently and that code path is projected to be
> backported. Can you check that trunk works for you?

Jim, just tested httpd-trunk (r1406270) and I can confirm that the issue is fixed now.

I am getting just this problem (AH01186: worker slotmem_grab failed) with 2.4.3 on Windows XP (64-bit).

The last comment seems to say that there is a fix, but I infer that it will require compiling from source. Is that correct?

That's right - you can build from sources to get this fixed or wait for the 2.4.4 release, which will fix the issue, see:
http://svn.apache.org/viewvc/httpd/httpd/branches/2.4.x/CHANGES?revision=1422877&view=markup

fixed in 2.4.4

Has this regressed somehow into 2.4.25 ?
I needed to change the config to have BalancerMember directives included within the VirtualHost.
When it is not done, on OSx I get 

[Thu May 04 16:54:49.918766 2017] [slotmem_shm:error] [pid 63687:tid 140736233759680] (24)Too many open files: AH02611: create: apr_shm_create(/somedir/logs/slotmem-shm-p3e3cb24c.shm) failed
[Thu May 04 16:54:49.918794 2017] [proxy_balancer:emerg] [pid 63687:tid 140736233759680] (24)Too many open files: AH01179: balancer slotmem_create failed