Closed
Bug 1186877
Opened 9 years ago
Closed 6 years ago
Fsync when writing to session-state.json
Categories
(Toolkit :: Telemetry, defect, P4)
Toolkit
Telemetry
Tracking
()
RESOLVED
INVALID
Tracking | Status | |
---|---|---|
firefox42 | --- | affected |
People
(Reporter: Dexter, Unassigned)
References
(Blocks 1 open bug)
Details
(Whiteboard: [unifiedTelemetry] [measurement:client])
We should decide if it's worth fsync session-state.json when using writeAtomic for extra safety (and small risk of jank).
If we decide to fsync, we should check with with bcolloran to set up an experiment to measure the benefit of the fsync and also measure the fsync cost with a Telemetry histogram.
So far, we have preferred to avoid using `fsync` in our code, except for extra-sensitive data. In the worst case scenario, how much data could we lose by not using `fsync`?
Reporter | ||
Comment 2•9 years ago
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||
In the worst case scenario, we could loose information about the previous subsession/session ids, which are helpful to create a sequence of sessions for Telemetry on the servers.
We would also loose the subsession counter for the current profile.
Would it be possible to attain the same level of safety by keeping a backup somewhere? For instance by not overwriting session-state.json, but moving it to session-state.old, and using session-state.old to reconstruct any data in case session-state.json is corrupted?
Comment 4•9 years ago
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That wouldn't improve things, we would still lose the chaining to the latest data.
I wonder if we can't find out if that is actually a significant problem?
Updated•9 years ago
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Reporter | ||
Updated•9 years ago
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Updated•9 years ago
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Priority: -- → P4
Whiteboard: [unifiedTelemetry] → [unifiedTelemetry] [measurement:client]
Comment 5•6 years ago
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I venture that since we've been living with this behaviour for four years we're probably okay with it :)
Status: NEW → RESOLVED
Closed: 6 years ago
Resolution: --- → INVALID
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Description
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