java.lang.IllegalStateException: Connection pool shut down

I am trying to post data to a REST service using Http and I have configured my client as follows:

PoolingHttpClientConnectionManager cm = new PoolingHttpClientConnectionManager();
        cm.setMaxTotal(60);
        cm.setDefaultMaxPerRoute(60);
        CloseableHttpClient httpclient = HttpClients.custom().setConnectionManager(cm).build();
        HttpPost httpPost = new HttpPost(url);
        httpPost.setHeader("Accept", "application/json");
        httpPost.setHeader("Content-type", "application/json");
        CloseableHttpResponse response = null;

Now I have an executor service which is responsible for calling the actual posting, I hand over the above params to Executor service as follows:

executor.execute(new LocalThreadPoolExecutor(line, client, httpPost,response ));

line is the JSON payload I am trying to send across.

Now my method in executor service looks like:

private void postData(String data, CloseableHttpClient client, HttpPost httpPost,
                         CloseableHttpResponse response) throws Exception {
        System.out.println("Post hit");
        StringEntity entity = new StringEntity(data);
        httpPost.setEntity(entity);
        response = client.execute(httpPost);
        int code = response.getStatusLine().getStatusCode();
        System.out.println("Stat" + code);

        logger.info("Response Code: " + code);

        String temp;
        String builder = "Response: ";
        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));

        while ((temp = bufferedReader.readLine()) != null) {
            builder = builder + (temp + "\n");
        }

        System.out.println(builder);
        //logger.info(payload);
        client.close();
    }

And and I am getting an exception at response = client.execute(httpPost);

Which is:

java.lang.IllegalStateException: Connection pool shut down
    at org.apache.http.util.Asserts.check(Asserts.java:34)
    at org.apache.http.pool.AbstractConnPool.lease(AbstractConnPool.java:189)
    at org.apache.http.impl.conn.PoolingHttpClientConnectionManager.requestConnection(PoolingHttpClientConnectionManager.java:257)
    at org.apache.http.impl.execchain.MainClientExec.execute(MainClientExec.java:176)
    at org.apache.http.impl.execchain.ProtocolExec.execute(ProtocolExec.java:185)
    at org.apache.http.impl.execchain.RetryExec.execute(RetryExec.java:89)
    at org.apache.http.impl.execchain.RedirectExec.execute(RedirectExec.java:111)
    at org.apache.http.impl.client.InternalHttpClient.doExecute(InternalHttpClient.java:185)
    at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:83)
    at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:108)
    at consumer.ril.com.LocalThreadPoolExecutor.postData(LocalThreadPoolExecutor.java:80)
    at consumer.ril.com.LocalThreadPoolExecutor.run(LocalThreadPoolExecutor.java:40)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:745)
java.lang.IllegalStateException: Connection pool shut down
    at org.apache.http.util.Asserts.check(Asserts.java:34)
    at org.apache.http.pool.AbstractConnPool.lease(AbstractConnPool.java:189)
    at org.apache.http.impl.conn.PoolingHttpClientConnectionManager.requestConnection(PoolingHttpClientConnectionManager.java:257)
    at org.apache.http.impl.execchain.MainClientExec.execute(MainClientExec.java:176)
    at org.apache.http.impl.execchain.ProtocolExec.execute(ProtocolExec.java:185)
    at org.apache.http.impl.execchain.RetryExec.execute(RetryExec.java:89)
    at org.apache.http.impl.execchain.RedirectExec.execute(RedirectExec.java:111)
    at org.apache.http.impl.client.InternalHttpClient.doExecute(InternalHttpClient.java:185)
    at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:83)
    at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:108)
    at consumer.ril.com.LocalThreadPoolExecutor.postData(LocalThreadPoolExecutor.java:80)
    at consumer.ril.com.LocalThreadPoolExecutor.run(LocalThreadPoolExecutor.java:40)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:745)

I know where the problem is, however I am unable to determine how to solve it!

Any help would be highly appreciated!