java.lang.OutOfMemoryError: Java heap space

[ERROR][o.e.b.ElasticsearchUncaughtExceptionHandler] [datacenter22] fatal error in thread [elasticsearch[datacenter22][bulk][T#30]], exiting
java.lang.OutOfMemoryError: Java heap space

[2017-09-11T11:23:00,453][WARN ][o.e.h.n.Netty4HttpServerTransport] [datacenter21] caught exception while handling client http traffic, closing connection [id: 0xea1dc2d3, L:/10.16.65.21:9200 - R:/10.16.65.13:44230]
java.lang.OutOfMemoryError: Java heap space
at io.netty.buffer.UnpooledHeapByteBuf.<init>(UnpooledHeapByteBuf.java:46) ~[?:?]
at io.netty.buffer.UnpooledByteBufAllocator.newHeapBuffer(UnpooledByteBufAllocator.java:59) ~[?:?]
at io.netty.buffer.AbstractByteBufAllocator.heapBuffer(AbstractByteBufAllocator.java:160) ~[?:?]
at io.netty.buffer.AbstractByteBufAllocator.heapBuffer(AbstractByteBufAllocator.java:151) ~[?:?]
at io.netty.buffer.Unpooled.buffer(Unpooled.java:116) ~[?:?]
--
at org.elasticsearch.common.util.concurrent.AbstractRunnable.run(AbstractRunnable.java:37) [elasticsearch-5.0.1.jar:5.0.1]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [?:1.8.0_102]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [?:1.8.0_102]
at java.lang.Thread.run(Thread.java:745) [?:1.8.0_102]