Attempting to trigger G1GC due to high heap usage – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 7.9-8.9

Briefly, this error occurs when Elasticsearch is trying to trigger the Garbage First Garbage Collector (G1GC) due to high heap usage. This means that the JVM heap space is almost full, which can lead to performance issues or even crashes. To resolve this issue, you can increase the heap size if your server has enough memory. Alternatively, you can optimize your queries or indices to reduce memory usage. Also, consider deleting unnecessary data or indices. Lastly, ensure that your Elasticsearch nodes are properly distributed and balanced to prevent memory overload on a single node.

This guide will help you check for common problems that cause the log ” attempting to trigger G1GC due to high heap usage [{}] ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: indices, breaker.

Log Context

Log “attempting to trigger G1GC due to high heap usage [{}]” classname is
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

                    long begin = timeSupplier.getAsLong();
                    leader = begin >= lastCheckTime + minimumInterval;
                    if (leader) {
                        long initialCollectionCount = gcCountSupplier.getAsLong();
              "attempting to trigger G1GC due to high heap usage [{}]"; memoryUsed.baseUsage);
                        long localBlackHole = 0;
                        // number of allocations; corresponding to (approximately) number of free regions + 1
                        int allocationCount = Math.toIntExact((maxHeap - memoryUsed.baseUsage) / g1RegionSize + 1);
                        // allocations of half-region size becomes single humongous alloc; thus taking up a full region.
                        int allocationSize = (int) (g1RegionSize >> 1);


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