Revert "Use singleton lock in LFGMgr v0.4. move LFG structures to singleton. must give some speedup and safety, but need test."

This reverts commit 681e8cadf39377905b776381374c9c63a0eb7535.
Use singleton lock in LFGMgr v0.5. move LFG structures to singleton. must give some speedup and safety, but need test.