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Fix CPU Usage Issues

System CPU alerts indicate that the CPU usage of the MongoDB process has reached a specified threshold. This threshold is specified when the alert is created.

Alert Conditions

You can configure the following alert conditions in the project-level alert settings page to trigger alerts.

System: CPU (Steal) %

Occurs when the percentage of time the CPU is in a state of “involuntary wait” exceeds the specified threshold. CPU steal percentage is the percentage by which the CPU usage exceeds the guaranteed baseline CPU credit accumulation rate.


This alert typically triggers when all credits have been consumed on an AWS burstable performance instance.

System: CPU (User) %
Occurs when the CPU usage of the MongoDB process, as normalized by the number of CPUs, exceeds the specified threshold.

Common Triggers

Unoptimized queries might lead to System CPU alerts.

Fix the Immediate Problem

Consider adding one or more indexes to improve query performance. For details on calculating suggested indexes, see Calculate Suggested Indexes.

Implement a Long-Term Solution

Consider scaling your cluster with additional servers to reduce the CPU usage percentage utilized by the current workload. For example, you could convert a replica set to a sharded cluster. To learn more about sharded clusters, see Sharding.

Monitor Your Progress

View the Normalized System CPU chart to monitor CPU usage of all processes on the node, scaled to a range of 0-100% by dividing by the number of CPU cores.

Monitor CPU usage to determine whether data is retrieved from disk instead of memory.

To learn more, see View Cluster Metrics.