I used dtruss on Eclipse Mars in the El Capitan public beta to see where it might be getting stuck. It seems like it's looping trying to get the current time, and failing.
sudo dtruss -p <PID>
gettimeofday(0x700001558C90, 0x0, 0x0) = 1436561967 0
gettimeofday(0x700001D70580, 0x0, 0x0) = 1436561967 0
gettimeofday(0x7FFF5FBFD2D0, 0x0, 0x100) = 1436561967 0
gettimeofday(0x7FFF5FBFDD10, 0x0, 0x100) = 1436561967 0
gettimeofday(0x7FFF5FBFCC20, 0x0, 0x100) = 1436561967 0
gettimeofday(0x7FFF5FBFE010, 0x0, 0x100) = 1436561967 0
gettimeofday(0x7FFF5FBFD2D0, 0x0, 0x100) = 1436561967 0
psynch_cvwait(0x10070D568, 0x100000100, 0x0) = -1 Err#316
psynch_cvwait(0x100644868, 0x100000100, 0x0) = -1 Err#316
gettimeofday(0x700001558C90, 0x0, 0x0) = 1436561967 0
gettimeofday(0x700001D70580, 0x0, 0x0) = 1436561967 0
psynch_cvwait(0x10070D568, 0x100000100, 0x0) = -1 Err#316
psynch_cvwait(0x100644868, 0x100000100, 0x0) = -1 Err#316
gettimeofday(0x700001558C90, 0x0, 0x0) = 1436561967 0
gettimeofday(0x700001D70580, 0x0, 0x0) = 1436561967 0
psynch_cvwait(0x100644868, 0x100000100, 0x0) = -1 Err#316
gettimeofday(0x700001558C90, 0x0, 0x0) = 1436561967 0
psynch_cvwait(0x10070D568, 0x100000100, 0x0) = -1 Err#316
gettimeofday(0x700001D70580, 0x0, 0x0) = 1436561967 0
psynch_cvwait(0x100644868, 0x100000100, 0x0) = -1 Err#316
gettimeofday(0x700001558C90, 0x0, 0x0) = 1436561967 0
psynch_cvwait(0x10070D568, 0x100000100, 0x0) = -1 Err#316
gettimeofday(0x700001D70580, 0x0, 0x0) = 1436561967 0
psynch_cvwait(0x100644868, 0x100000100, 0x0) = -1 Err#316
gettimeofday(0x700001558C90, 0x0, 0x0) = 1436561967 0
psynch_cvwait(0x10070D568, 0x100000100, 0x0) = -1 Err#316
gettimeofday(0x700001D70580, 0x0, 0x0) = 1436561967 0
psynch_cvwait(0x100644868, 0x100000100, 0x0) = -1 Err#316
psynch_cvwait(0x10070D568, 0x100000100, 0x0) = -1 Err#316
gettimeofday(0x700001558C90, 0x0, 0x0) = 1436561967 0
gettimeofday(0x700001D70580, 0x0, 0x0) = 1436561967 0
psynch_cvwait(0x100644868, 0x100000100, 0x0) = -1 Err#316
psynch_cvwait(0x10070D568, 0x100000100, 0x0) = -1 Err#316
gettimeofday(0x700001558C90, 0x0, 0x0) = 1436561967 0
gettimeofday(0x700001D70580, 0x0, 0x0) = 1436561967 0