Tarantool troubleshooting¶

Sections below provide the information about frequent errors in Tarantool operation and their troubleshooting.

How can I solve the "readahead limit reached" problem?¶

In the /var/log/wallarm/tarantool.log or /opt/wallarm/var/log/wallarm/tarantool-out.log file depending on a node installation method, you may get errors like:

readahead limit reached, stopping input on connection fd 16, 
aka 127.0.0.1:3313, peer of 127.0.0.1:53218

This problem is not critical but too many such errors may decrease the service performance.

To solve the problem:

Access the /usr/share/wallarm-tarantool/init.lua folder → box.cfg file.
Set one of the following:
- readahead = 1*1024*1024
- readahead = 8*1024*1024

The readahead parameter defines the size of the read-ahead buffer associated with a client connection. The larger the buffer, the more memory an active connection consumes and the more requests can be read from the operating system buffer in a single system call. See more details in the Tarantool documentation.

How can I solve the "net_msg_max limit is reached" problem?¶

In the /var/log/wallarm/tarantool.log or /opt/wallarm/var/log/wallarm/tarantool-out.log file depending on a node installation method, you may get errors like:

2020-02-18 12:22:17.420 [26620] iproto iproto.cc:562 W> stopping input on connection fd 21, 
aka 127.0.0.1:3313, peer of 127.0.0.1:44306, net_msg_max limit is reached

To solve the problem, increase the value of net_msg_max (default value 768):

Access the /usr/share/wallarm-tarantool/init.lua folder → box.cfg file.
Increase the net_msg_max value, for example:
```
box.cfg {
    net_msg_max = 6000
}
```

To prevent fiber overhead from affecting the whole system, the net_msg_max parameter restricts how many messages the fibers handle. See details on using net_msg_max in the Tarantool documentation.