Hi Costin,
it wasn't difficult, so here is the new patch. The new (old) behavior is:
The main worker is defined by a lb_value of 0. This will never be changed in
jk_lb_worker. The other workers can get a value greater than 0. If the value
from config file is less than 0 it is multiplicated with -1.
Your are right this is a better solution. We can switch from doubles to int and
we get the other worker balanced if the main worker is down.
Bernd
Bernd Koecke wrote:
> Hi Costin,
>
> [EMAIL PROTECTED] wrote:
>
>> Hi Bernd,
>>
>> First, many thanks for your help :-)
>>
>>
>
> your welcome, its a lot of fun :)
>
>>> No, I think not :). I checked it yesterday. With some additional log
>>> statements in the validate function of jk_lb_worker.c you get the
>>> value _inf_ for the lb_factor and lb_value (line 434-444). Because if
>>> it would be set to 1, my config hadn't worked. Because I set the
>>> local worker to 1 and the others to 0.
>>
>>
>>
>> I'll check again, and fix it if necesarry.
>>
>> I wrote some code in jk2 that seems to solve the problem, and I can
>> backport this to jk1 if it is correct.
>>
>> Probably this is my mistake - I remember the discussion and the patch
>> that was sent for this problem, and most likely I did something
>> wrong commiting it ( i.e. I did few changes trying to simplify it, and it
>> seems I 'simplified' too much ). But my memory still has the patch's
>> logic
>> which seemed fine :-)
>>
>>
>>> This is possible, but then you must add a check if the value is 0.
>>> Because without it you calc 1/0 with an int and this will give you an
>>> error.
>>
>>
>>
>> Yes, of course. 0 will continue to mean 'default worker'.
>>
>
> see below
>
>> I'm not very comfortable with float calculations in the critical
>> path ( and in an area that is executed concurently !). The only problem
>> is what happens on overflows - the lb_value may become 0 ( or a small
>> value ) and then the worker will take all the load.
>>
>>
>>> Thats not the whole story. Its right you will check the main worker
>>> when its back again and use it only once. Because when the request
>>> was successful handled rec->in_recovering is true (line 332 of
>>> jk_lb_worker.c, service function). Than get_max_lb get the value
>>> _inf_ from one of the other worker. Than the things happen which I
>>> said in my prior mail.
>>
>>
>>
>>> That was it what I did in my sent patch, the additional documentation
>>> was sent a few days later. But my additions to the lb_worker were a
>>> little bit to complex. You are right we should get it when we use the
>>> flag only on the main worker and change the behavior after a failure
>>> for this worker. But we need the trick with 0/inf for the other
>>> worker, because only with this we have the situation that the other
>>> worker wouldn't be asked when there is no session and the main worker
>>> is up.
>>
>>
>>
>>
>> Ok, can you send the patch again :-) ?
>> For going back to the main worker - if we let it with lb_value=0 at all
>> time ( i.e. we don't alter that at any time ), and only in_error_state
>> is set on failure - then I believe the thing will work fine.
>>
>>
>
> Thats the invers from the actual situation. So my patch from a few hours
> earlier this day depends on the fact that the other worker get a
> lb_value of 0 in the config file. This will be converted to _inf_ and
> the main worker gets 1 and this will be the minimal lb_value of the
> balanced workers. If we want the possibility to switch to ints I could
> send a new patch which handles 0 as a special value for the main worker.
>
> Should I?
>
> Bernd
>
>
>>
>>> I will try to build another patch and send it. I think it could be
>>> possible without an additional flag.
>>
>>
>>
>> Great !
>>
>>
>>
>>> Another tought about this:
>>> When you use double and we fix the handling after an error, the main
>>> worker would never reach _inf_. Because the lb_factor is < 1 if
>>> lb_value wasn't 0. After choosing the worker this value is added to
>>> the lb_value. But with a high value for lb_value the differenc
>>> between two savable double numbers is greater than the lb_factor. But
>>> this is only interessting in theory. I think in real world we will
>>> reboot apache before this will happen :).
>>
>>
>>
>> That may become a problem if we use ints.
>>
>> Costin
>>
>>
>>
> [...]
>
>
--
Dipl.-Inform. Bernd Koecke
UNIX-Entwicklung
Schlund+Partner AG
Fon: +49-721-91374-0
E-Mail: [EMAIL PROTECTED]
Index: jk_lb_worker.c
===================================================================
RCS file: /home/cvspublic/jakarta-tomcat-connectors/jk/native/common/jk_lb_worker.c,v
retrieving revision 1.8
diff -u -r1.8 jk_lb_worker.c
--- jk_lb_worker.c 12 Jan 2002 05:27:39 -0000 1.8
+++ jk_lb_worker.c 3 May 2002 17:17:35 -0000
@@ -291,7 +291,12 @@
}
}
- if(rc) {
+ /*
+ * The following isn't necessary, because for the 'main' worker
+ * lb_value and lb_factor are == 0. And all other worker have a value > 0
+ * But it makes the intention clearer.
+ */
+ if(rc && rc->lb_value != 0) {
rc->lb_value += rc->lb_factor;
}
@@ -329,7 +334,7 @@
int src = end->service(end, s, l, &is_recoverable);
end->done(&end, l);
if(src) {
- if(rec->in_recovering) {
+ if(rec->in_recovering && rec->lb_value != 0) {
rec->lb_value = get_max_lb(p->worker) +
ADDITINAL_WAIT_LOAD;
}
rec->in_error_state = JK_FALSE;
@@ -433,13 +438,23 @@
p->lb_workers[i].name = jk_pool_strdup(&p->p, worker_names[i]);
p->lb_workers[i].lb_factor = jk_get_lb_factor(props,
worker_names[i]);
- p->lb_workers[i].lb_factor = 1/p->lb_workers[i].lb_factor;
+ if (p->lb_workers[i].lb_factor < 0) {
+ p->lb_workers[i].lb_factor = -1 * p->lb_workers[i].lb_factor;
+ }
+ if (0 < p->lb_workers[i].lb_factor) {
+ p->lb_workers[i].lb_factor = 1/p->lb_workers[i].lb_factor;
+ }
/*
* Allow using lb in fault-tolerant mode.
* Just set lbfactor in worker.properties to 0 to have
* a worker used only when principal is down or session route
* point to it. Provided by Paul Frieden <[EMAIL PROTECTED]>
*/
+ /*
+ * The above comment should be fixed because it is vice versa:
+ * A worker with lb_factor == 0 is always asked and only with a
+ * session another worker would get the request
+ */
p->lb_workers[i].lb_value = p->lb_workers[i].lb_factor;
p->lb_workers[i].in_error_state = JK_FALSE;
p->lb_workers[i].in_recovering = JK_FALSE;
--
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