Vladislav, Ged:

Reloading select databases is not feasible at this time, because signatures are 
loaded into the same structures in memory and that entire thing is recreated on 
reload.

Regarding the threaded reload feature ( ticket: 
https://bugzilla.clamav.net/show_bug.cgi?id=10979 )...

The main reason the "threaded reload" patch is held back at present is 
primarily because the recent work and interest in the patch came at the same 
time that 0.102 development was in code freeze while we tested and applied bug 
fixes for release.  Reloading in a separate thread means that the memory usage 
will double (going from roughly ~750MB to ~1500MB) during the reload before it 
frees the original signatures and drops back to ~750MB.  

We already have many complaints about freshclam and clamd memory usage, and 
this change in behavior could cause trouble for some users, so we want to 
provide an option to reload the traditional way.  That's the second reason why 
the patch isn't been merged for 0.103 yet.  We have to dedicate some time to 
code the ability to reload either way.  It is absolutely on our to-do list. 

Regarding the increase in daily.cvd signatures causing slow load times...

We identified the cause of slow load times.  There are 2 loading algorithms 
identified that are inefficient and causing slow load times.  The first has to 
do with signature ignore lists.  This is easier to address for all users and 
I'm currently waiting for a larger update to daily & main that will drop load 
time by about 40% or so for most users.  The 2nd is something harder to solve, 
triggered by 2 very common patterns in our signature set, used to identify 
functions and VBA macros.  I was spending most of my time trying to figure out 
if we can optimize the signatures to get around the design issue, but had 
limited success. Alberto Wu, meanwhile, has found a way to make the loading 
algorithm more efficient (posted just yesterday).  

His patch is really promising, though I'm still testing in a very large 
regression test and sorting through a large number of detection changes to 
identify the cause.  For details, please read this ticket: 
https://bugzilla.clamav.net/show_bug.cgi?id=12389 I'll continue to update that 
ticket as testing continues and I review the results. 

Best regards,
Micah

On 10/17/19, 11:08 AM, "clamav-users on behalf of Vladislav Kurz via 
clamav-users" <clamav-users-boun...@lists.clamav.net on behalf of 
clamav-users@lists.clamav.net> wrote:

    On 17/10/2019 16:51, G.W. Haywood via clamav-users wrote:
    > Hi there,
    > 
    > On Thu, 17 Oct 2019, Vladislav Kurz via clamav-users wrote:
    > 
    >> So the question is - what would be easier to code?
    >> - reloading in background thread
    >> - reloading limited to new files
    > 
    > It is not clear to me that the latter suggestion is feasible, but...
    > 
    > 1. Reload in a separate thread was first coded about six years ago.
    > 
    > 2. After other, more recent discussions on this list some weeks ago,
    >    I provided a patch for the current version of clamd, using that
    >    original code as a basis.  Yet more recently, one of the ClamAV
    >    developers provided a similar patch.  Both are freely available.
    > 
    > 3. I've been running the patched code without issue for months.
    
    Oh great. Thank you Ged for writing and testing it. I apologise for not
    noticing that these patch is already done. Is there anything blocking
    this patch from being accepted ?
    
    I'm noticing clamav-reload related timeouts on more and more (mostly
    older or low-end) servers, which were running just fine a year or two ago.
    
    -- 
    Best regards
            Vladislav Kurz
    
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