[CDRIVER-1958] Change in compression usage between 1.3.5 and 1.4 Created: 19/Dec/16  Updated: 27/Oct/23  Resolved: 19/Dec/16

Status: Closed
Project: C Driver
Component/s: Performance
Affects Version/s: None
Fix Version/s: None

Type: Task Priority: Major - P3
Reporter: Lorne Schachter Assignee: Unassigned
Resolution: Works as Designed Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Related
related to CDRIVER-1369 Set SSL_OP_NO_COMPRESSION by default Closed

 Description   

Customer created 419679 to look at performance differences between C driver 1.3.5 and 1.4. They followed up with flame graphs showing that 1.3.5 was using compression and 1.4 does not seem to be. They note that the SSL support was rewritten in 1.4 and ask if compression by default was turned off (and if so, how to turn it back on).



 Comments   
Comment by Hannes Magnusson [ 19/Dec/16 ]

See https://github.com/mongodb/mongo-c-driver/blob/master/src/mongoc/mongoc-openssl.c#L472-L481 if they want to patch the client manually.

Comment by Hannes Magnusson [ 19/Dec/16 ]

We have no plans to add TLS Compression as an option as not all libraries we support support it, and infact the only library that currently supports it is phasing its use out and the latest versions don't support it.

We are however working on wire protocol compression in clients, which can be enabled/disabled independently of TLS compression.
This implementation would likely work back to the current MongoDB 3.2 release, although it will likely be flagged as a MongoDB 3.4 feature.

Note that this feature is in the specification process for clients, so not guaranteed just yet.

Comment by Hannes Magnusson [ 19/Dec/16 ]

It was indeed disabled, and its not possible to enable it (see CDRIVER-1369).
Even if we would provide such switch then it would magically disappear when they upgrade to OpenSSL 1.1.0.

Out of curiosity, which distribution are they running that has compression enabled? I it very difficult to find such distro these days so I'd be very interesting in reproing this.

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