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# 17 Upgrade notes for 7.0.6

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#### Asynchronous poller state calculation

Asynchronous pollers are now considered busy if they have reached the limit set by the MaxConcurrentChecksPerPoller [server](/manual/appendix/config/zabbix_server#maxconcurrentchecksperpoller)/[proxy](/manual/appendix/config/zabbix_proxy#maxconcurrentchecksperpoller) configuration parameter.
Utilization of poller processes can be monitored with the [zabbix[process,,,]](/manual/config/items/itemtypes/internal#process) internal item.

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#### StartPreprocessors default increased

The default value of the StartPreprocessors [server](/manual/appendix/config/zabbix_server#startpreprocessors)/[proxy](/manual/appendix/config/zabbix_proxy#startpreprocessors) configuration parameter has been increased from 3 to 16.
To make the best use of available resources, the number of pre-started instances of preprocessing worker threads should be set to at least match the number of available CPU cores.
If preprocessing tasks are not CPU-bound and involve frequent network requests, configuring additional workers is recommended.

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