In my Linux environment, the HashSessionIdManager in its default configuration hangs on startup, preventing Jetty from starting up (and binding to a port, etc.). As inspected through JConsole, the SessionIdManager is in the 'starting' state, but never reaches the 'started' state. The stack trace of the 'main' thread is as follows: # Stack trace: # java.io.FileInputStream.readBytes(Native Method) # java.io.FileInputStream.read(FileInputStream.java:199) # java.io.BufferedInputStream.read1(BufferedInputStream.java:256) # java.io.BufferedInputStream.read(BufferedInputStream.java:317) # java.io.BufferedInputStream.fill(BufferedInputStream.java:218) # java.io.BufferedInputStream.read1(BufferedInputStream.java:258) # java.io.BufferedInputStream.read(BufferedInputStream.java:317) # sun.security.provider.SeedGenerator$URLSeedGenerator.getSeedByte(SeedGenerator.java:453) # sun.security.provider.SeedGenerator.getSeedBytes(SeedGenerator.java:123) # sun.security.provider.SeedGenerator.generateSeed(SeedGenerator.java:118) # sun.security.provider.SecureRandom.engineGenerateSeed(SecureRandom.java:114) # sun.security.provider.SecureRandom.engineNextBytes(SecureRandom.java:171) # java.security.SecureRandom.nextBytes(SecureRandom.java:433) # java.security.SecureRandom.next(SecureRandom.java:455) # java.util.Random.nextLong(Random.java:284) # org.mortbay.jetty.servlet.HashSessionIdManager.doStart(HashSessionIdManager.java:105) # org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:40) # org.mortbay.jetty.servlet.AbstractSessionManager.doStart(AbstractSessionManager.java:166) # org.mortbay.jetty.servlet.HashSessionManager.doStart(HashSessionManager.java:53) Some googling revealed that there was a known issue with SecureRandom on Linux in prior versions of the JDK, which was configured to read from /dev/random, which is blocking on Linux. Indeed /dev/random does block, however under 1.5 and 1.6, the configuration has changed to use /dev/urandom. I also tested explicitly setting the java.security.egd property to file:/dev/urandom. Neither of these solve the problem. Ultimately I found a solution: explicitly passing a java.util.Random (NOT a java.security.SecureRandom) to the HashSessionIdManager: <Set name="sessionIdManager"> <New class="org.mortbay.jetty.servlet.HashSessionIdManager"> <Arg> <!-- MUST explicitly set to java.util.Random --> <New class="java.util.Random"/> </Arg> <Set name="workerName">node1</Set> </New> </Set> There are several possible issues here: 1. Maybe User Mode Linux is somehow interfering with the JDK SecureRandom API. Despite all settings appearing to be correct (and a test case using SecureRandom appearing to work), HashSessionIdManager still hangs by default. 2. HashSessionIdManager (or some other jetty code) is doing something nefarious...like trying to read /dev/random and blocking (interestingly, JConsole indicated that the main thread was not blocked, but running...) 3. This is simply "known behavior" that is not documented anywhere. If so, it should be documented because it is very difficult to diagnose. I can reproduce this on-demand if needed. Thank you