Mailing List Archive

JT Justman wrote:
> Hi, everyone. I've been doing my best to dig into the bug I opened:
>
> http://varnish.projects.linpro.no/ticket/240
>
> Basically, every object is inserted, but the second and subsiquent
> objects always miss.

I have found the cause for the bug, and a potential fix.

In cache_hash.c function HSH_Lookup, there is a ttl check:

if (o->ttl >= sp->t_req)

This test passes on the first ESI and fails on the others. Debugging
shows that the ttl is correct, but t_req is NAN. It seems that t_req is
cleared, and needs to be reset somewhere in ESI or the step flow.

My solution is to set sp->t_req = TIM_real() in ESI_Deliver. (See patch).

Not being intimate with the program flow or timing, I don't know what
other implications this could have. Suggestions?

JT
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Can you try this patch instead:


Index: cache_center.c
===================================================================
--- cache_center.c (revision 2639)
+++ cache_center.c (working copy)
@@ -234,7 +234,6 @@
sp->xid = 0;
SES_Charge(sp);
sp->t_open = sp->t_end;
- sp->t_req = NAN;
sp->t_resp = NAN;
WSL_Flush(sp->wrk, 0);

@@ -242,6 +241,8 @@
if (sp->esis > 0)
return (1);

+ sp->t_req = NAN;
+
if (sp->fd >= 0 && sp->doclose != NULL)
vca_close_session(sp, sp->doclose);
if (sp->fd < 0) {



Poul-Henning


In message <4833000D.3010204 at endpoint.com>, JT Justman writes:
>This is a multi-part message in MIME format.
>--------------020006040805080601000507
>Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>Content-Transfer-Encoding: 7bit
>
>JT Justman wrote:
>> Hi, everyone. I've been doing my best to dig into the bug I opened:
>>
>> http://varnish.projects.linpro.no/ticket/240
>>
>> Basically, every object is inserted, but the second and subsiquent
>> objects always miss.
>
>I have found the cause for the bug, and a potential fix.
>
>In cache_hash.c function HSH_Lookup, there is a ttl check:
>
>if (o->ttl >= sp->t_req)
>
>This test passes on the first ESI and fails on the others. Debugging
>shows that the ttl is correct, but t_req is NAN. It seems that t_req is
>cleared, and needs to be reset somewhere in ESI or the step flow.
>
>My solution is to set sp->t_req = TIM_real() in ESI_Deliver. (See patch).
>
>Not being intimate with the program flow or timing, I don't know what
>other implications this could have. Suggestions?
>
>JT
>
>--------------020006040805080601000507
>Content-Type: text/x-diff;
> name="cache_vrt_esi-jt_2008-05-20.patch"
>Content-Transfer-Encoding: 7bit
>Content-Disposition: inline;
> filename="cache_vrt_esi-jt_2008-05-20.patch"
>
>Index: cache_vrt_esi.c
>===================================================================
>--- cache_vrt_esi.c (revision 2635)
>+++ cache_vrt_esi.c (working copy)
>@@ -773,6 +773,8 @@
> obj = sp->obj;
> sp->obj = NULL;
> *sp->http = *sp->http0;
>+ if (isnan(sp->t_req))
>+ sp->t_req = TIM_real();
> /* XXX: reset sp->ws */
> http_SetH(sp->http, HTTP_HDR_URL, eb->include.b);
> if (eb->host.b != NULL) {
>
>--------------020006040805080601000507
>Content-Type: text/plain; charset="us-ascii"
>MIME-Version: 1.0
>Content-Transfer-Encoding: 7bit
>Content-Disposition: inline
>
>_______________________________________________
>varnish-dev mailing list
>varnish-dev at projects.linpro.no
>http://projects.linpro.no/mailman/listinfo/varnish-dev
>
>--------------020006040805080601000507--
>

--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

Can you try this patch instead:


Index: cache_center.c
===================================================================
--- cache_center.c (revision 2639)
+++ cache_center.c (working copy)
@@ -234,7 +234,6 @@
sp->xid = 0;
SES_Charge(sp);
sp->t_open = sp->t_end;
- sp->t_req = NAN;
sp->t_resp = NAN;
WSL_Flush(sp->wrk, 0);

@@ -242,6 +241,8 @@
if (sp->esis > 0)
return (1);

+ sp->t_req = NAN;
+
if (sp->fd >= 0 && sp->doclose != NULL)
vca_close_session(sp, sp->doclose);
if (sp->fd < 0) {



Poul-Henning


In message <4833000D.3010204 at endpoint.com>, JT Justman writes:
>This is a multi-part message in MIME format.
>--------------020006040805080601000507
>Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>Content-Transfer-Encoding: 7bit
>
>JT Justman wrote:
>> Hi, everyone. I've been doing my best to dig into the bug I opened:
>>
>> http://varnish.projects.linpro.no/ticket/240
>>
>> Basically, every object is inserted, but the second and subsiquent
>> objects always miss.
>
>I have found the cause for the bug, and a potential fix.
>
>In cache_hash.c function HSH_Lookup, there is a ttl check:
>
>if (o->ttl >= sp->t_req)
>
>This test passes on the first ESI and fails on the others. Debugging
>shows that the ttl is correct, but t_req is NAN. It seems that t_req is
>cleared, and needs to be reset somewhere in ESI or the step flow.
>
>My solution is to set sp->t_req = TIM_real() in ESI_Deliver. (See patch).
>
>Not being intimate with the program flow or timing, I don't know what
>other implications this could have. Suggestions?
>
>JT
>
>--------------020006040805080601000507
>Content-Type: text/x-diff;
> name="cache_vrt_esi-jt_2008-05-20.patch"
>Content-Transfer-Encoding: 7bit
>Content-Disposition: inline;
> filename="cache_vrt_esi-jt_2008-05-20.patch"
>
>Index: cache_vrt_esi.c
>===================================================================
>--- cache_vrt_esi.c (revision 2635)
>+++ cache_vrt_esi.c (working copy)
>@@ -773,6 +773,8 @@
> obj = sp->obj;
> sp->obj = NULL;
> *sp->http = *sp->http0;
>+ if (isnan(sp->t_req))
>+ sp->t_req = TIM_real();
> /* XXX: reset sp->ws */
> http_SetH(sp->http, HTTP_HDR_URL, eb->include.b);
> if (eb->host.b != NULL) {
>
>--------------020006040805080601000507
>Content-Type: text/plain; charset="us-ascii"
>MIME-Version: 1.0
>Content-Transfer-Encoding: 7bit
>Content-Disposition: inline
>
>_______________________________________________
>varnish-dev mailing list
>varnish-dev at projects.linpro.no
>http://projects.linpro.no/mailman/listinfo/varnish-dev
>
>--------------020006040805080601000507--
>

--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.