Skip to main content

Java HttpServer OutOfMemory Issue

We had to extract text out of documents that people were uploading to the site so we can index them. As this was going to be just a text extraction services I didnt wanted to go for some full blown tomcat server so wrote a quick http server using java

        this.httpServer = HttpServer.create(addr, 0);
        HttpContext context = this.httpServer.createContext("/", new DocumentProcessHandler());
        this.httpThreadPool = Executors.newFixedThreadPool(this.noOfThreads);
        context.getFilters().add(new HttpParameterFilter());
Not adding all code for brevity. 

After being live for 2-3 days the process started crashing and it was a regular pattern. I added -verbose:gc -XX:+HeapDumpOnOutOfMemoryError to the startup script and had a crash dump after 3 days. Using eclipse Memory Analyzer and using Histogram to look at the heap dump revealed that we had 90K HttpConnection objects. wow that looks for sure like a leak.

I tried everything from closing the exchange, responseBody as shown below but the connections would remain.

    class DocumentProcessHandler implements HttpHandler {
        public void handle(HttpExchange exchange) throws IOException {
                PrintWriter responseBody = new PrintWriter(exchange.getResponseBody());

                try {
..........code removed for brevity of post....................
                } catch (Throwable t) {
                    throw new IOException(t);
                } finally {

To prove my theory I send few http requests and did jmap -histo:live 16315 |grep http and keep on seeing the http connections would increase after every requests.
This is definitely a bug in the HttpServer code so use it only for demos and not for production use. I saw that lots of other people are also facing same issues and sun wont agree that its a bug so I am again moving back to tomcat :).


  1. I find out if the HTTP GET request has some extra bytes after the last 0xd 0xa in the HTTP header, it could lead to this leak as the HttpConnection is not added to "idleConnections" in

  2. Another relevant bug report:;?bug_id=6946825


Post a Comment

Popular posts from this blog

RabbitMQ java clients for beginners

Here is a sample of a consumer and producer example for RabbitMQ. The steps are
Download ErlangDownload Rabbit MQ ServerDownload Rabbit MQ Java client jarsCompile and run the below two class and you are done.
This sample create a Durable Exchange, Queue and a Message. You will have to start the consumer first before you start the for the first time.

For more information on AMQP, Exchanges, Queues, read this excellent tutorial
import com.rabbitmq.client.Connection; import com.rabbitmq.client.Channel; import com.rabbitmq.client.*; public class RabbitMQProducer { public static void main(String []args) throws Exception { ConnectionFactory factory = new ConnectionFactory(); factory.setUsername("guest"); factory.setPassword("guest"); factory.setVirtualHost("/"); factory.setHost(""); factory.setPort(5672); Conne…

Spring query timeout or transaction timeout

If you are using spring to manage transactions then you can specify default transaction timeout using

    <bean id="transactionManager"
        <property name="dataSource" ref="dataSource" />
        <property name="defaultTimeout" value="30" /> <!--30 sec--->             

or you can override the timeout in the annotation

    @Transactional(readOnly = false, timeout=30)

or if you are doing it programatic transactions then you can do

DataSourceTransactionManager transactionManager = new DataSourceTransactionManager(dataSource);

 or you can override the timeout for one particular transaction

TransactionTemplate transactionTemplate = new TransactionTemplate();

Python adding pid file

I have a thumbnail generator that launches multiple processes and the correct way to shut it down is to send kill -HUP to the parent process. To automate I had to write a pid file from python, it was a piece of cake
def writePidFile(): pid = str(os.getpid()) f = open('', 'w') f.write(pid) f.close()