NPE in SSLSocketImpl.getEnabledCipherSuites

NPE in SSLSocketImpl.getEnabledCipherSuites

I am using Apache HTTP client in multiple workers, and it looks like there
is some kind of race condition (stacktrace is at the end). I am puzzled as
googling the stacktrace does not provide any hint (yet). Using Java
1.7.0-b147 64bits on Linux.
Am I doing something wrong here?
Are there known, efficient alternatives to Sun's implementations of
SSLSocket?
Stacktrace:
java.lang.NullPointerException
at
sun.security.ssl.SSLSocketImpl.getEnabledCipherSuites(SSLSocketImpl.java:2320)
at javax.net.ssl.SSLSocket.getSSLParameters(SSLSocket.java:614)
at sun.security.ssl.SSLSocketImpl.getSSLParameters(SSLSocketImpl.java:2406)
at
sun.security.ssl.SSLAlgorithmConstraints.<init>(SSLAlgorithmConstraints.java:65)
at sun.security.ssl.Handshaker.init(Handshaker.java:236)
at sun.security.ssl.Handshaker.<init>(Handshaker.java:191)
at sun.security.ssl.ClientHandshaker.<init>(ClientHandshaker.java:104)
at sun.security.ssl.SSLSocketImpl.initHandshaker(SSLSocketImpl.java:1217)
at sun.security.ssl.SSLSocketImpl.doneConnect(SSLSocketImpl.java:634)
at sun.security.ssl.SSLSocketImpl.connect(SSLSocketImpl.java:608)
at
org.apache.http.conn.ssl.SSLSocketFactory.connectSocket(SSLSocketFactory.java:414)
at
org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:180)
at
org.apache.http.impl.conn.ManagedClientConnectionImpl.open(ManagedClientConnectionImpl.java:294)
at
org.apache.http.impl.client.DefaultRequestDirector.tryConnect(DefaultRequestDirector.java:643)
at
org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:479)
at
org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:906)
at
org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:805)
at
org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:784)