While performing simultaneous activities I was able to put a mongod 1.5.6 instance into a supposed deadlock. The server still accepts connections but will not perform further queries or mapreduces. I've included a currentOp output and a portion of stdout and stderr from mongod. Samples of the types of mapreduces and queries used can be gleaned from this output. The server was under heavy use with many processes/hosts concurrently querying and inserting and performing mapreduces.

The mongod and the system is idle. I've tried interrupting the server with a response of "got kill or ctrl c or hup signal 2 (Interrupt), will terminate after current cmd ends". I've issued db.killOp requests which do not take effect.