THRIFT-5914: Disable lingering for the Ruby server and configure client

[kpumuk]

Caution

This pull request introduces lingering settings aligned with C++ library, but upon further investigation does not seem to be safe. For example, THRIFT-3888 talks about abnormal connection termination from the client side.

Implemented lingering the same way C++ library handles it:

• completely disabled for the server https://github.com/apache/thrift/blob/master/lib/cpp/src/thrift/transport/TServerSocket.cpp#L335-L342
• enabled for the client but with timeout of 0 seconds https://github.com/apache/thrift/blob/master/lib/cpp/src/thrift/transport/TSocket.cpp#L101-L102

Lingering for the client can be configured:

socket = Thrift::Socket.new('localhost', port)
# Disable lingering
socket.linger(false, 0)
# Enable lingering with timeout 10 seconds
socket.linger(true, 10)

Benchmark

Before:

THRIFT_NUM_CALLS=1 THRIFT_NUM_CLIENTS=1000 THRIFT_SERVER=Thrift::ThreadPoolServer ruby benchmark/benchmark.rb; netstat -n | wc -l
Starting server...
Spawning benchmark processes...
Collecting output...
Translating output...
Analyzing output...

Server class:        Thrift::ThreadPoolServer
Server interpreter:  ruby
Client interpreter:  ruby
Socket class:        Thrift::Socket
Number of processes: 40
Clients per process: 1000
Calls per client:    1
Using fastthread:    no

Connection failures:               0
Connection errors:                 0
Average time per call:             0.0080 seconds
Average time per client (1 calls): 0.0082 seconds
Total time for all calls:          319.6949 seconds
Real time for benchmarking:        9.1044 seconds
Shortest call time:                0.0001 seconds
Longest call time:                 0.0229 seconds
Shortest client time (1 calls):    0.0003 seconds
Longest client time (1 calls):     0.2283 seconds

====> 13714 open sockets afterwards in TIME_WAIT status

After:

$ THRIFT_NUM_CALLS=1 THRIFT_NUM_CLIENTS=1000 THRIFT_SERVER=Thrift::ThreadPoolServer ruby benchmark/benchmark.rb; netstat -n | wc -l
Starting server...
Spawning benchmark processes...
Collecting output...
Translating output...
Analyzing output...

Server class:        Thrift::ThreadPoolServer
Server interpreter:  ruby
Client interpreter:  ruby
Socket class:        Thrift::Socket
Number of processes: 40
Clients per process: 1000
Calls per client:    1
Using fastthread:    no

Connection failures:               0
Connection errors:                 0
Average time per call:             0.0083 seconds
Average time per client (1 calls): 0.0084 seconds
Total time for all calls:          330.7904 seconds
Real time for benchmarking:        9.2939 seconds
Shortest call time:                0.0001 seconds
Longest call time:                 0.0245 seconds
Shortest client time (1 calls):    0.0003 seconds
Longest client time (1 calls):     0.2390 seconds

====> 4 open sockets afterwards, ~85 in the process

• Did you create an Apache Jira ticket? THRIFT-5914
• If a ticket exists: Does your pull request title follow the pattern "THRIFT-NNNN: describe my issue"?
• Did you squash your changes to a single commit? (not required, but preferred)
• Did you do your best to avoid breaking changes? If one was needed, did you label the Jira ticket with "Breaking-Change"?
• If your change does not involve any code, include [skip ci] anywhere in the commit message to free up build resources.

[kpumuk]

Found this ticket and now I am questioning both this and C++ implementation: https://issues.apache.org/jira/browse/THRIFT-3888

Java does not set lingering on the server socket, but instead disables it on the client, and it is not configurable: https://github.com/apache/thrift/blob/master/lib/java/src/main/java/org/apache/thrift/transport/TSocket.java#L63

Going to switch this to draft and perform more analysis...

[kpumuk]

Stress-testing with so_linger(1, 0) on a benchmark with 40,000 separate calls in multiple processes, closing and re-opening the socket for each call leads to actual data loss on oneway RPC - 0-4 calls out of 40,000.

[kpumuk]

Current state in other libraries, omitted ones do not configure lingering (off by default)

Language	Server	Client	Notes
c_glib			Proposed, and then deleted here THRIFT-2414
cpp	[0, 0]	[1, 0]	Issues with terminating connections THRIFT-3888, in WSL THRIFT-5374
d	[0, 0]
delphi	[0, 0]	[1, 0]
java		[0, 0]
netstd			Intentionally not used, see THRIFT-904