Once the critical-heap-percentage is exceeded, operations do not complete, and instead throwing throw a LowMemoryException for Region.put(), Region.create(), Region.putAll(), any index creation operation, and at the execution of any function. This continues until the tenured heap usage falls more than 2% below the configured critical-heap-percentage, at which point the system returns to normal operation without intervention.
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Be aware that exceeding the threshold on one member may affect other members. With operations not completing, the system may those other members may believe that the member exceeding the threshold has crashed; they may then take further action and revoke the membership of the member that is above the critical-heap-percentage. This can cause the remaining members to increase their usage of memory to compensate for the missing member. If these remaining members are not sized to handle the increased load, the critical heap threshold issue may cascade through the system.
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