Issue with nchan and Android clients

[SimonFair]

Currently I have noticed that the number of stored messages increases until memory is exhausted, issue is from Android clients and then selecting another tab in the client browser. Tried to set expiry for messages but then dont seem to get purged.

#
# Listen on local socket for nchan publishers
#
server {
    listen unix:/var/run/nginx.socket default_server;
    location ~ /pub/(.*)$ {
        nchan_publisher;
        nchan_channel_id "$1";
        nchan_message_buffer_length $arg_buffer_length;
        nchan_message_timeout 15s;
    }
    location ~ /nchan_stub_status$ {
        nchan_stub_status;
    }
}

Every 1.0s: curl --unix-socket /var/run/nginx.socket http://localhost/nchan_stub_status computenode: Sun Mar 20 13:48:47 2022

% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
0 0 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0 100 384 100 384 0 0 3289k 0 --:--:-- --:--:-- --:--:-- 375k
total published messages: 42200
stored messages: 1879
shared memory used: 14908K
shared memory limit: 131072K
channels: 27
subscribers: 9
redis pending commands: 0
redis connected servers: 0
total interprocess alerts received: 0
interprocess alerts in transit: 0
interprocess queued alerts: 0
total interprocess send delay: 0
total interprocess receive delay: 0
nchan version: 1.2.15

[SimonFair]

Any suggestions of ideas to try?

[slact]

How much shared memory does Nchan have? What is the message publishing rate and average size?

[SimonFair]

nchan has 131072K allocated.

When it is running as expected outstanding messages are low

total published messages: 323326
stored messages: 8
shared memory used: 72K
shared memory limit: 131072K

Issue comes when an android device or similar is used on the page and the device goes stops processing the page, the messages start to build up to the point it exceeds the available memory. The subscriber is still connected.

I have tried add buffer length and timeout to the server but does not seem to make a difference.

  #
    # Listen on local socket for nchan publishers
    #
    server {
        listen unix:/var/run/nginx.socket default_server;
        location ~ /pub/(.*)$ {
            nchan_publisher;
            nchan_channel_id "$1";
            nchan_message_buffer_length 1;
            nchan_message_timeout 1s;
        }
        location ~ /nchan_stub_status$ {
            nchan_stub_status;
        }
    }

Message sizes are smallish around 4k

total published messages: 333099
stored messages: 462
shared memory used: 632K
shared memory limit: 131072K
channels: 15
subscribers: 8
redis pending commands: 0
redis connected servers: 0
redis unhealthy upstreams: 0
total redis commands sent: 0
total interprocess alerts received: 0
interprocess alerts in transit: 0
interprocess queued alerts: 0
total interprocess send delay: 0
total interprocess receive delay: 0
nchan version: 1.3.6

[slact]

What subscriber type do these devices use?

[SimonFair]

I guess you mean websocket?

var vmdashusage = new NchanSubscriber('/sub/vm_dashusage',{subscriber:'websocket'});

[slact]

Yes, thanks. What about the subscriber location block in your config?

[SimonFair]

# Listen on local socket for nchan publishers
#
server {
    listen unix:/var/run/nginx.socket default_server;
    location ~ /pub/(.*)$ {
        nchan_publisher;
        nchan_channel_id "$1";
        nchan_message_buffer_length 1;
        nchan_message_timeout 1s;
    }
    location ~ /nchan_stub_status$ {
        nchan_stub_status;
    }
}

[SimonFair]

function publish($endpoint, $message, $len=1) {
$com = curl_init("http://localhost/pub/$endpoint?buffer_length=$len");
curl_setopt_array($com,[
CURLOPT_UNIX_SOCKET_PATH => "/var/run/nginx.socket",
CURLOPT_HTTPHEADER => ['Accept:text/json'],
CURLOPT_POST => 1,
CURLOPT_POSTFIELDS => $message,
CURLOPT_RETURNTRANSFER => 1
]);
$reply = curl_exec($com);
curl_close($com);
if ($reply===false) my_logger("curl to $endpoint failed", 'publish');
return $reply;
}

[slact]

That's the publisher location. I'm interested in the subscriber location, the one containing nchan_subscriber or nchan_pubsub.

[SimonFair]

    #
    # nchan subscriber endpoint
    #
    location ~ /sub/(.*)$ {
        nchan_subscriber;
        # nchan_authorize_request <url here>
        nchan_channel_id "$1";
        nchan_channel_id_split_delimiter ",";
    }
    location /nchan_stub_status {
        nchan_stub_status;
    }

[SimonFair]

@slact any suggestions on what to try?

[slact]

If your traffic permits it, please run Nchan with 1 worker process and see if that makes a difference.

[SimonFair]

If your traffic permits it, please run Nchan with 1 worker process and see if that makes a difference.

grep worker_processes /etc/nginx/nginx.conf
worker_processes 1;