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JIT-unspill: fix potential deadlock #501

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merged 1 commit into from
Jan 27, 2021
Merged

JIT-unspill: fix potential deadlock #501

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23 changes: 12 additions & 11 deletions dask_cuda/proxify_host_file.py
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Original file line number Diff line number Diff line change
Expand Up @@ -209,7 +209,7 @@ def __delitem__(self, key):
del self.store[key]
self.proxies_tally.del_key(key)

def evict(self, proxy):
def evict(self, proxy: ProxyObject):
proxy._obj_pxy_serialize(serializers=("dask", "pickle"))

def maybe_evict(self, extra_dev_mem=0):
Expand All @@ -219,13 +219,14 @@ def maybe_evict(self, extra_dev_mem=0):
):
return

total_dev_mem_usage, dev_buf_access = self.get_access_info()
total_dev_mem_usage += extra_dev_mem
if total_dev_mem_usage > self.device_memory_limit:
dev_buf_access.sort(key=lambda x: (x[0], -x[1]))
for _, size, proxies in dev_buf_access:
for p in proxies:
self.evict(p)
total_dev_mem_usage -= size
if total_dev_mem_usage <= self.device_memory_limit:
break
with self.lock:
total_dev_mem_usage, dev_buf_access = self.get_access_info()
total_dev_mem_usage += extra_dev_mem
if total_dev_mem_usage > self.device_memory_limit:
dev_buf_access.sort(key=lambda x: (x[0], -x[1]))
for _, size, proxies in dev_buf_access:
for p in proxies:
self.evict(p)
total_dev_mem_usage -= size
if total_dev_mem_usage <= self.device_memory_limit:
break
22 changes: 14 additions & 8 deletions dask_cuda/proxy_object.py
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Original file line number Diff line number Diff line change
Expand Up @@ -107,13 +107,12 @@ def _obj_pxy_cache_wrapper(attr_name):
def wrapper1(func):
@functools.wraps(func)
def wrapper2(self: "ProxyObject"):
with self._obj_pxy_lock:
try:
return self._obj_pxy_cache[attr_name]
except KeyError:
ret = func(self)
self._obj_pxy_cache[attr_name] = ret
return ret
try:
return self._obj_pxy_cache[attr_name]
except KeyError:
ret = func(self)
self._obj_pxy_cache[attr_name] = ret
return ret

return wrapper2

Expand Down Expand Up @@ -299,7 +298,14 @@ def _obj_pxy_deserialize(self):
# to evict because of the increased device memory usage.
if "cuda" not in self._obj_pxy["serializers"]:
if hostfile is not None:
hostfile.maybe_evict(self.__sizeof__())
# In order to avoid a potential deadlock, we skip the
# `maybe_evict()` call if another thread is also accessing
# the hostfile.
if hostfile.lock.acquire(blocking=False):
try:
hostfile.maybe_evict(self.__sizeof__())
finally:
hostfile.lock.release()
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Note for future reading: hostfile.lock is an RLock, so this block is ok.


header, frames = self._obj_pxy["obj"]
self._obj_pxy["obj"] = distributed.protocol.deserialize(header, frames)
Expand Down