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The following commit(s) were added to refs/heads/trunk by this push:
new 66cf90a75a Clarify stale on_fork() comments in copyutil.py
66cf90a75a is described below
commit 66cf90a75a2e9d7865c756f6d1f50fcc3d3f201e
Author: Arvind Kandpal <[email protected]>
AuthorDate: Tue Sep 8 11:58:43 2026 +0530
Clarify stale on_fork() comments in copyutil.py
Windows code was already removed in CASSANDRA-16956, but the
comments were left as an open question. Channels/generators must
still be created after fork, not in __init__ - a thread doesn't
survive fork and isn't picklable on spawn platforms like macOS
(CASSANDRA-11053, CASSANDRA-11701). Comment-only change.
patch by Arvind Kandpal; reviewed by Bernardo Botella, Bret McGuire for
CASSANDRA-17350
---
pylib/cqlshlib/copyutil.py | 23 ++++++++++++++---------
1 file changed, 14 insertions(+), 9 deletions(-)
diff --git a/pylib/cqlshlib/copyutil.py b/pylib/cqlshlib/copyutil.py
index 9586486af1..6f534d6240 100644
--- a/pylib/cqlshlib/copyutil.py
+++ b/pylib/cqlshlib/copyutil.py
@@ -878,7 +878,7 @@ class FilesReader(object):
self.max_rows = options.copy['maxrows']
self.skip_rows = options.copy['skiprows']
self.fname = fname
- self.sources = None # might be initialised directly here? (see
CASSANDRA-17350)
+ self.sources = None # created lazily in start(): a generator can't be
pickled for spawn (CASSANDRA-11053)
self.num_sources = 0
self.current_source = None
self.num_read = 0
@@ -1294,9 +1294,9 @@ class FeedingProcess(mp.Process):
self.inpipe = inpipe
self.outpipe = outpipe
self.worker_pipes = worker_pipes
- self.inmsg = None # might be initialised directly here? (see
CASSANDRA-17350)
- self.outmsg = None # might be initialised directly here? (see
CASSANDRA-17350)
- self.worker_channels = None # might be initialised directly here?
(see CASSANDRA-17350)
+ self.inmsg = None # created in on_fork(): must run in the child,
after start(), not here
+ self.outmsg = None # created in on_fork(): must run in the child,
after start(), not here
+ self.worker_channels = None # created in on_fork(): must run in the
child, after start(), not here
self.reader = FilesReader(fname, options) if fname else
PipeReader(inpipe, options)
self.send_meter = RateMeter(log_fcn=None, update_interval=1)
self.ingest_rate = options.copy['ingestrate']
@@ -1306,8 +1306,10 @@ class FeedingProcess(mp.Process):
def on_fork(self):
"""
- Create the channels and release any parent connections after forking,
- see CASSANDRA-11749 for details.
+ Create the channels here, not in __init__, since __init__ runs in the
+ parent before start(). Threads don't survive fork and aren't picklable
+ for spawn, and creating the feeding thread lazily once caused a race
+ between senders (CASSANDRA-11701). See CASSANDRA-17350 for details.
"""
self.inmsg = ReceivingChannel(self.inpipe)
self.outmsg = SendingChannel(self.outpipe)
@@ -1402,8 +1404,8 @@ class ChildProcess(mp.Process):
super(ChildProcess, self).__init__(target=target)
self.inpipe = params['inpipe']
self.outpipe = params['outpipe']
- self.inmsg = None # might be initialised directly here? (see
CASSANDRA-17350)
- self.outmsg = None # might be initialised directly here? (see
CASSANDRA-17350)
+ self.inmsg = None # created in on_fork(): must run in the child,
after start(), not here
+ self.outmsg = None # created in on_fork(): must run in the child,
after start(), not here
self.ks = params['ks']
self.table = params['table']
self.local_dc = params['local_dc']
@@ -1440,7 +1442,10 @@ class ChildProcess(mp.Process):
def on_fork(self):
"""
- Create the channels and release any parent connections after forking,
see CASSANDRA-11749 for details.
+ Create the channels here, not in __init__, since __init__ runs in the
+ parent before start(). Threads don't survive fork and aren't picklable
+ for spawn, and creating the feeding thread lazily once caused a race
+ between senders (CASSANDRA-11701). See CASSANDRA-17350 for details.
"""
self.inmsg = ReceivingChannel(self.inpipe)
self.outmsg = SendingChannel(self.outpipe)
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