[squid-users] squid in container aborted on low memory server

[Alex Rousskov]

On 3/3/19 9:39 PM, George Xie wrote:

> Squid version: 3.5.23-5+deb9u1

>     http_port 127.0.0.1:3128
>     cache deny all
>     access_log none

Unfortunately, this configuration wastes RAM: Squid is not yet smart
enough to understand that you do not want any caching and may allocate
256+ MB of memory cache plus supporting indexes. To correct that default
behavior, add this:

      cache_mem 0

Furthermore, older Squids, possibly including your no-longer-supported
version, may allocate shared memory indexes where none are needed. That
might explain why you see your Squid allocating a 392 MB table.

If you want to know what is going on for sure, then configure malloc to
dump core on allocation failures and post a stack trace leading to that
allocation failure so that we know _what_ Squid was trying to allocate
when it ran out of RAM.


HTH,

Alex.


> runs in a container with following Dockerfile:
> 
>     FROM debian:9
>     RUN apt update && \
>     apt install --yes squid
> 
> 
> the total memory of the host server is very low, only 592m, about 370m
> free memory.
> if I start squid in the container, squid will abort immediately. 
> 
> error messages in /var/log/squid/cache.log:
> 
> 
>     FATAL: xcalloc: Unable to allocate 1048576 blocks of 392 bytes!
> 
>     Squid Cache (Version 3.5.23): Terminated abnormally.
>     CPU Usage: 0.012 seconds = 0.004 user + 0.008 sys
>     Maximum Resident Size: 47168 KB
> 
> 
> error message captured with strace -f -e trace=memory:
> 
>     [pid   920] mmap(NULL, 411176960, PROT_READ|PROT_WRITE,
>     MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = -1 ENOMEM (Cannot allocate memory)
> 
> 
> it appears that squid (or glibc) tries to allocate 392m memory, which is
> larger than host free memory 370m.
> but I guess squid don't need that much memory, I have another running
> squid instance, which only uses < 200m memory.
> the oddest thing is if I run squid on the host (also Debian 9) directly,
> not in the container, squid could start and run as normal.
> 
> am I doing something wrong thing here?
> 
> Xie Shi
> 
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