Changing KeepAlive to Off does not help, the issue occurs at this
point where obviously due to MaxConnectionsPerChild a Process
should become killed.

As observed, the problem is that (in the example stated) both
PIDs 11454 and 16555 do not become killed because of these
remaining connections, which is ok, since these could be
remaining downloads or something to a client.
But then, Apache does neither fork new processes to accept
new connections nor does it kill the both PIDs (which is as just
statet, ok) - the scoreboard is full then in that case and new
connections can not be accepted.

As I see a solution to this problem is that the main httpd process
should be 1. able to fork new processes 2. I see no reason why
the scoreboard is full then, 1+2 connections is 3, not 2x64=128,
in that given case 125 free slots are wasted since they are blocked
by the 2 remaining processes which show connections which fill up
the scoreboard, those are shown as "G"s in the scoreboard for both
PIDs - that should not be the case.

Since 2.4.2 (the first I've used) I did not understand why a
finishing/killing process shows all "G"s - however, that issue did
not occur in 2.2 when I used MPM event in experimental stage, but
in 2.2 I did not have that problem, the connections were counted as
usual. Probably because lots of the code was taken from MPM worker,
where the calculations were still correct, until fully adopted to 2.4.

By this theory, also MPM worker might experience this, however, due to
the different design MPM worker also may never get to that point to
show this behavior and error messages in the log.

So my conclusion is also a question: why are finishing processes showing
all "G"s in the scoreboard, and/or why are these finishing threads all
counted in the scoreboard (here: 2x64 instead of 1+2, causing 125 threads
to be wasted).

I would expect this issue to become much more important when most people
upgrade to 2.4, also I clearly would say this is a bug.

On Thu, Sep 6, 2012 at 11:21 PM, Sam <lenn...@chello.at <mailto:lenn...@chello.at>> wrote:

    Never, the server is not even under high load. There
    are several thousand vhosts, it is about shared webhosting.

    This is what server-status says:

    PID    Connections     Threads    Async connections
    total    accepting    busy    idle    writing    keep-alive    closing
    21388    257    yes  44   20    0  171   44
    11454    2      no    0    0    0    0    0
    16555    1      no    0    0    0    0    0
    Sum      260         44   20    0  171   44


How about those 171 in keep-alive? What are your KeepAlive and KeepAliveTimeout settings? Maybe try switching KeepAlive off? Whit only 192 threads and KeepAlive On you are imposing DoS on your self in case of long timeout.

    That one PID 11454has "2" connections, 16555 has "1", all other
    values are 0, I guess it should become killed?  - but it does not,
    it stays like this for a while (I don't know on what this "while"
    depends on).

    At this point all 3 rows are filled with stuff, such as:

    WWW_W_WWWWWW_WW_W_W_W_WW__WWW__WW__WWWWWW__WWW__W__W_RWWWWRWWWWW
    GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG
    GGGGGGGGGGGGGGGLGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG

    But as you see, due to several _ this means that there are
    not all 192 busy, in fact:

    105 requests/sec - 2.5 MB/second - 24.8 kB/request
    44 requests currently being processed, 20 idle workers

    WHY can no others be used? With the statement above it means that
    128 (which is 192-64) workers are unused because they should become
    killed already, to spawn new ones, these are the ones in the 2. and
    3. row with "G"s.

    --

    So the rest is occupied with "G". In Apache 2.2 I used MPM_event
    as well, this obviously never occured because the both PIDs above
    which are showing G only showed just dots in that case, now after
    one PID should be finished, all slots become occupied with G,
    which obviously causes a full scoreboard.

    I would consider this a bug, a serious one for my case, since it
    often occurs (~1-3 times per hour) that the server stops accepting
    new requests, just because of that full scoreboard, where the server
    is neither busy, nor do I see what configuration directive should
    be configured badly. Again:

    KeepAlive                   On
    ListenBacklog             4095
    Timeout                     20
    KeepAliveTimeout             8
    MaxKeepAliveRequests     16192
    MaxRanges                  200
    MaxRangeOverlaps            20
    MaxRangeReversals           20
    GracefulShutdownTimeout      6
    LimitInternalRecursion      10
    LimitRequestFieldSize     4094
    LimitRequestFields          40
    LimitRequestLine          4094
    LimitXMLRequestBody     786432

    MaxRequestWorkers 192
    ServerLimit         3
    StartServers        2

    MaxMemFree                2048
    MinSpareThreads             64
    MaxSpareThreads             64
    ThreadLimit                128
    ThreadsPerChild             64
    MaxConnectionsPerChild   10240
    AsyncRequestWorkerFactor    10


    I assumed AsyncRequestWorkerFactor to have something to do
    with it, I raised it from 2 (default) to 10, no change.

    By the way: after some time (in this case above both) PIDs
    become killed finally, releasing 2x64 slots in the scoreboard,
    the waring messages vanish and the server can respond again
    well to requests. In the interest of finding a workaround until
    this is fixed: what configuration directives control that timeout
    or whatever, which cause these PIDs to become killed?



    On Thu, Sep 6, 2012 at 7:06 PM, Sam <lenn...@chello.at
    <mailto:lenn...@chello.at>> wrote:


        Yes, I still see such messages even after upgrading to 2.4.3

        On Sun, Aug 19, 2012 at 8:25 AM, Sam<lenn...@chello.at>  
<mailto:lenn...@chello.at>  wrote:
        I upgraded to Apache 2.4 and use mod_event on a server
        having average high load.

        My issue is that I am getting pretty much often the error message
        within the error log

        AH00485: scoreboard is full, not at MaxRequestWorkers

        What causes this? The server almost stops to handle new requests
        when this occurs.

        MaxRequestWorkers 192
        ServerLimit         3
        StartServers        2

        MaxMemFree                2048
        MinSpareThreads             64
        MaxSpareThreads             64
        ThreadLimit                 64
        ThreadsPerChild             64
        MaxConnectionsPerChild   10240
        AsyncRequestWorkerFactor     2


    So you never have more than 192 simultaneous requests at any
    given time ???




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