@Override
    public void exceptionCaught(final ChannelHandlerContext ctx, final Throwable cause) {
        logger.error("Error processing HTTP Request", cause);

        if (ctx.channel().isActive()) {
            HttpHandlerUtil.sendError(ctx, INTERNAL_SERVER_ERROR, cause.getMessage());
        }
    }
Tracks the rate of pause to writes when the high watermark is exceeded.
gremlin-server/src/main/java/org/apache/tinkerpop/gremlin/server/handler/HttpGremlinEndpointHandler.java