io_collect_interval

The instance will sleep for io_collect_interval seconds between iterations of the event loop. Can be used to reduce CPU load in deployments in which the number of client connections is large, but requests are not so frequent (for example, each connection issues just a handful of requests per second).

Type: float
Default: null
Dynamic: yes
net_msg_max

To handle messages, Tarantool allocates fibers. To prevent fiber overhead from affecting the whole system, Tarantool restricts how many messages the fibers handle, so that some pending requests are blocked.

On powerful systems, increase net_msg_max and the scheduler will immediately start processing pending requests.

On weaker systems, decrease net_msg_max and the overhead may decrease although this may take some time because the scheduler must wait until already-running requests finish.

When net_msg_max is reached, Tarantool suspends processing of incoming packages until it has processed earlier messages. This is not a direct restriction of the number of fibers that handle network messages, rather it is a system-wide restriction of channel bandwidth. This in turn causes restriction of the number of incoming network messages that the transaction processor thread handles, and therefore indirectly affects the fibers that handle network messages. (The number of fibers is smaller than the number of messages because messages can be released as soon as they are delivered, while incoming requests might not be processed until some time after delivery.)

On typical systems, the default value (768) is correct.

Type: integer
Default: 768
Dynamic: yes
readahead

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. The rule of thumb is to make sure the buffer can contain at least a few dozen requests. Therefore, if a typical tuple in a request is large, e.g. a few kilobytes or even megabytes, the read-ahead buffer size should be increased. If batched request processing is not used, it’s prudent to leave this setting at its default.

Type: integer
Default: 16320
Dynamic: yes