我们遇到了导致服务器挂起的问题，我们进行了一次线程转储，发现大约有200多个线程具有以下信息：等待锁定<0x00000006cf5fadc0>
"Keep-Alive-Timer" #32300 daemon prio=8 os_prio=0 tid=0x00007ff994392800 nid=0x7aba waiting for monitor entry [0x00007ff915357000]
java.lang.Thread.State: BLOCKED (on object monitor)
at sun.net.www.http.KeepAliveCache.run(KeepAliveCache.java:174)
- waiting to lock <**0x00000006cf5fadc0**> (a sun.net.www.http.KeepAliveCache)
at java.lang.Thread.run(Thread.java:748)
Locked ownable synchronizers:
- None
"http-/0.0.0.0:18280-594 XCID=a5139447-2199-4ce7-84c7-3e9b180de92f SEQ=0" #32211 daemon prio=5 os_prio=0 tid=0x0000000001167000 nid=0x7381 waiting for monitor entry [0x00007ff90110e000]
java.lang.Thread.State: BLOCKED (on object monitor)
at sun.net.www.http.KeepAliveCache.get(KeepAliveCache.java:156)
- waiting to lock <**0x00000006cf5fadc0**> (a sun.net.www.http.KeepAliveCache)
at sun.net.www.http.HttpClient.New(HttpClient.java:303)
at sun.net.www.http.HttpClient.New(HttpClient.java:357)
at sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(HttpURLConnection.java:1220)
at sun.net.www.protocol.http.HttpURLConnection.plainConnect0(HttpURLConnection.java:1156)
at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:1050)
at sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:984)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1564)
- locked <0x000000078adf2180> (a sun.net.www.protocol.http.HttpURLConnection)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1492)
- locked <0x000000078adf2180> (a sun.net.www.protocol.http.HttpURLConnection)
at java.net.HttpURLConnection.getResponseCode(HttpURLConnection.java:480)
at com.sun.jersey.client.urlconnection.URLConnectionClientHandler._invoke(URLConnectionClientHandler.java:249)
at com.sun.jersey.client.urlconnection.URLConnectionClientHandler.handle(URLConnectionClientHandler.java:149)
at com.sun.jersey.api.client.Client.handle(Client.java:648)
at com.sun.jersey.api.client.WebResource.handle(WebResource.java:680)
at com.sun.jersey.api.client.WebResource.access$200(WebResource.java:74)
at com.sun.jersey.api.client.WebResource$Builder.method(WebResource.java:621)
但是，我们没有找到任何线程保持锁<0x00000006cf5fadc0>，有人可以告诉我为什么吗？
谢谢