The parent circuit breaker trip in this log entry and in this case it means the existing JVM Heap usage level is already too high to be able to run a task which gets rejected to avoid Out-Of-Memory
Most likely given elasticsearch JVM Heap Space was only 1Gb in this case, you should increase JVM Heap Space further to a level where the is no longer memory pressure issues (up to maximum of 50% of RAM or 30Gb whichever is lowest)...