I just got another JVM (1.8) dead lock from htmlunit 2.25. Found one Java-level deadlock: "JS executor for com.gargoylesoftware.htmlunit.WebClient@14abd28e": waiting to lock monitor 0x00007f69e00259d8 (object 0x00007f6ddfc45070, a com.gargoylesoftware.htmlunit.html.HtmlPage), which is held by "pool-30545-thread-1" "pool-30545-thread-1": waiting to lock monitor 0x00007f69901b6668 (object 0x00007f6de04873b8, a com.gargoylesoftware.htmlunit.html.HtmlPage), which is held by "JS executor for com.gargoylesoftware.htmlunit.WebClient@14abd28e"...