"http-apr-7001-exec-41" daemon prio=6 tid=0x0000000015999800 nid=0x50a0 in Object.wait() [0x000000002d79b000]
   java.lang.Thread.State: WAITING (on object monitor)
    at java.lang.Object.wait(Native Method)
    at java.lang.Object.wait(Object.java:503)
    at java.net.InetAddress.checkLookupTable(Unknown Source)
    - locked <0x000000071387bcc0> (a java.util.HashMap)
    at java.net.InetAddress.getAddressesFromNameService(Unknown Source)
    at java.net.InetAddress.getAllByName0(Unknown Source)
    at java.net.InetAddress.getAllByName(Unknown Source)
    at java.net.InetAddress.getAllByName(Unknown Source)
    at org.apache.http.impl.conn.SystemDefaultDnsResolver.resolve(SystemDefaultDnsResolver.java:45)
    at org.apache.http.impl.conn.DefaultHttpClientConnectionOperator.connect(DefaultHttpClientConnectionOperator.java:111)
    at org.apache.http.impl.conn.PoolingHttpClientConnectionManager.connect(PoolingHttpClientConnectionManager.java:353)
    at org.apache.http.impl.execchain.MainClientExec.establishRoute(MainClientExec.java:380)
    at org.apache.http.impl.execchain.MainClientExec.execute(MainClientExec.java:236)
    at org.apache.http.impl.execchain.ProtocolExec.execute(ProtocolExec.java:184)
    at org.apache.http.impl.execchain.RetryExec.execute(RetryExec.java:88)
    at org.apache.http.impl.execchain.RedirectExec.execute(RedirectExec.java:110)
    at org.apache.http.impl.client.InternalHttpClient.doExecute(InternalHttpClient.java:184)
    at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:82)
    at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:107)

    private static InetAddress[] checkLookupTable(String host) {
        synchronized (lookupTable) {
            // If the host isn't in the lookupTable, add it in the
            // lookuptable and return null. The caller should do
            // the lookup.
            if (lookupTable.containsKey(host) == false) {
                lookupTable.put(host, null);
                return null;
            }

            // If the host is in the lookupTable, it means that another
            // thread is trying to look up the addresses of this host.
            // This thread should wait.
            while (lookupTable.containsKey(host)) {
                try {
                    lookupTable.wait();
                } catch (InterruptedException e) {
                }
            }
        }