javax.ws.rs.ProcessingException: RESTEASY004655: Unable to invoke request

I reuse the builder , but multiple threads accessing the same client, I get the following exception:

Exception in thread "Thread-2" javax.ws.rs.ProcessingException: RESTEASY004655: Unable to invoke request
at org.jboss.resteasy.client.jaxrs.engines.ApacheHttpClient4Engine.invoke(ApacheHttpClient4Engine.java:289)
at org.jboss.resteasy.client.jaxrs.internal.ClientInvocation.invoke(ClientInvocation.java:454)
at org.jboss.resteasy.client.jaxrs.internal.ClientInvocationBuilder.get(ClientInvocationBuilder.java:157)
at RestClientDemo.send(RestClientDemo.java:28)
at RestClientDemo.send(RestClientDemo.java:11)
at RestClientDemo$ThreadDemo2.run(RestClientDemo.java:40)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.IllegalStateException: Connection is still allocated
at org.apache.http.util.Asserts.check(Asserts.java:34)
at org.apache.http.impl.conn.BasicHttpClientConnectionManager.getConnection(BasicHttpClientConnectionManager.java:266)
at org.apache.http.impl.conn.BasicHttpClientConnectionManager$1.get(BasicHttpClientConnectionManager.java:217)
at org.apache.http.impl.execchain.MainClientExec.execute(MainClientExec.java:190)
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:55)
at org.jboss.resteasy.client.jaxrs.engines.ApacheHttpClient4Engine.invoke(ApacheHttpClient4Engine.java:285)
... 6 more