The deadlock was caused in transfermap.go by calling mu.RLock() in one
function then calling it again in a sub function. Normally this is
fine, however this leaves a window where mu.Lock() can be called. When
mu.Lock() is called it doesn't allow the second mu.RLock() and
deadlocks.
Thead 1 Thread 2
String():mu.RLock()
del():mu.Lock()
sortedSlice():mu.RLock() - DEADLOCK
Lesson learnt: don't try using locks recursively ever!
This patch fixes the problem by removing the second mu.RLock(). This
was done by factoring the code that was calling it into the
transfermap.go file so all the locking can be seen at once which was
ultimately the cause of the problem - the code which used the locks
was too far away from the rest of the code using the lock.
This problem was introduced in:
bfa5715017 fs/accounting: sort transfers by start time
Which hasn't been released in a stable version yet
This is preparation for getting the Accounting to check the context,
buf first we need to get it in place. Since this is one of those
changes that makes lots of noise, this is in a seperate commit.
For few commands, RClone counts a error multiple times. This was fixed by
creating a new error type which keeps a flag to remember if the error has
already been counted or not. The CountError function now wraps the original
error eith the above new error type and returns it.
In 53a1a0e3ef we introduced a problem where if there was an
error on the file being transferred then the file was re-opened and
the old one wasn't closed.
This was partially fixed in bfbddab46b however this didn't
address the case of the old file being closed.
This is now fixed by
- marking the file as open again in UpdateReader
- moving the stopping the accounting machinery to a new method Done
Before this change, using -P occasionally deadlocked on the Transfer
mutex when Transfer.Done() was called with a non nil error and the
StatsInfo mutex since they mutually call each other.
This was fixed by making sure that the Transfer mutex is always
released before calling any StatsInfo methods.
This improves on: 6f87267b34Fixes#3505
Before this change, using -P occasionally deadlocked on the transfer
mutex and the stats mutex since they call each other via the progress
printing.
This is fixed by shortening the locking windows and converting the
mutex to a RW mutex.
This is done to make clear ownership over accounting object and prepare
for removing global stats object.
Stats elapsed time calculation has been altered to account for actual
transfer time instead of stats creation time.
