If it exceeds the setting value of the max-connections(max of connection), you need use available connection(overConnection) temporarily.
It has been waited for certain amount of time(connection-wait-time) to check whether normal connection is reusable if overConnection is acquired.
Connection is acquired as overConnection if reusable connection cannot be acquired for certain amount of time.
The following error is output in "system.log" and "exception.log"
if it is over max-connections + max-overflow-connections(max of overConnection).
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Connection pool is full.
Can't allocate connection.
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Moreover, when process delays due to a setting value of the max-connections, causes might be inappropriateness (too less) of max-connections settings, the state until exceeds, or the operation environment.
For example, when capabilities on the DB side is low and the respond speed is slow, the state of the connection being used continues. As a result, it might exceeds the setting value of the max-connections.
For this reason, to set the max-connections appropriately, it is required to understand the capability and the state of the operation environment and the connection state to set an appropriate value for the operation environment.
*The Resin Admin function of Resin can be used to grasp the state of the operation environment on the application side to some extent.
Setting method and so on for Resin Admin is described in the developer’s blog below. Please refer to it.
・intra-mart Advent Calendar 2013 Day 9: Introduction of Resin Admin
https://dev.intra-mart.jp/blog/intra-mart_advent_calendar_2013_9resin_admin/
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iAP/Accel Platform/All Updates
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