Currently I'm running nntpcached on a somewhat memory-starved system.
Users were complaining that it took too long for trn or tin to start
up. As these times varied from 20 minutes to ten hours, I had to
agree. It turns out that there's a simple performance modification
that can be made to improve the common-case scenario: requesting the
active file entry for a single, specific group. Rather than scanning
through the entire active list sequentially, doing a glob match
against each one, the patch notices when there are no metacharacters
in the pattern and traverses the hash table/tree to get directly to
the desired group.
FWIW, that full search takes about a minute and a half. Repeat for
every subscribed-to group at newsreader startup time, and you can see
why it might take a really long time to get through that part. This
is, of course, only a problem on memory-starved systems. It has no
effect on the initial startup delay (twenty minutes for us). This is
purely a memory system problem with no obvious and straight-forward
work-around.
I made the change in 1.0.1, but diff'ing against 1.0.5 shows no
other changes in the relevant part of list.c. Therefore, I suspect
this will work on any of the 1.0.* versions to date.
The hash table size should also be increased, but since our server is
already tight on memory, I haven't done this as yet. Our upstream
provider has 41000 groups, and the distributed hash table size is
31337. A more appropriate value would be something like 100313, to
allow a little more room for growth.
Dworkin
================================================================
*** ../nntpcache-1.0.5/list.c Fri Feb 28 19:54:10 1997
--- list.c Tue Apr 22 15:15:23 1997
***************
*** 473,478 ****
--- 440,490 ----
emitrn (NNTP_XGTITLE_OK);
else
emitrn (NNTP_LIST_FOLLOWS);
+ #if 1
+ if (group_pat!=NULL && strchr(group_pat, '*')==NULL && strchr(group_pat, '?')==NULL)
+ {
+ struct newsgroup *p = newsgroup_find_add(group_pat, NULL, FALSE);
+ if (p != NULL)
+ {
+ switch (list->type)
+ {
+ case l_active:
+ {
+ int hi, lo;
+ if (!p->moderation)
+ break;
+ hi = MAX(p->hi, p->hi_server);
+ if (p->lo>0)
+ lo = p->lo;
+ else
+ lo = 0;
+ if (p->lo_server>0)
+ {
+ if (lo>0)
+ lo = MIN(lo, p->lo_server);
+ else
+ lo = p->lo_server;
+ }
+ emitf ("%s %d %d %c\r\n", p->group, hi, lo, p->moderation);
+ break;
+ }
+ case l_active_times:
+ if (p->creation_time && p->creator)
+ emitf ("%s %lu %s\r\n", p->group, p->creation_time, p->creator);
+ break;
+ case l_xgtitle:
+ case l_newsgroups:
+ if (p->desc)
+ emitf ("%s\t%s\r\n", p->group, p->desc);
+ break;
+ default:
+ break;
+ }
+ }
+ emitrn (".");
+ return TRUE;
+ }
+ #endif
for (n=Ni->newsgroup_head; n; n=n->next)
{
#ifdef READ_LOCKS
