ekg
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-with-rtsopts=-T results in severe slowdown
Just ran a few tests on a small Servant app and got these results:
# with -with-rtsopts=-T
Lifting the server siege...
Transactions: 2131 hits
Availability: 100.00 %
Elapsed time: 19.58 secs
Data transferred: 0.05 MB
Response time: 0.45 secs
Transaction rate: 108.84 trans/sec
Throughput: 0.00 MB/sec
Concurrency: 49.41
Successful transactions: 2131
Failed transactions: 0
Longest transaction: 0.60
Shortest transaction: 0.02
# without -with-rtsopts=-T
Lifting the server siege...
Transactions: 4699 hits
Availability: 100.00 %
Elapsed time: 19.73 secs
Data transferred: 0.10 MB
Response time: 0.21 secs
Transaction rate: 238.17 trans/sec
Throughput: 0.01 MB/sec
Concurrency: 49.67
Successful transactions: 4699
Failed transactions: 0
Longest transaction: 0.31
Shortest transaction: 0.03
Haven't looked into it too much closer, but the setup between the two is entirely identical except for the -with-rtsopts=-T
arg.
I'll try to extract something out into a more concrete repro, but I was pretty surprised when I saw it as the README suggests that the option should be pretty innocuous.
This is probably more apprioriate for the GHC bug tracker.
Was any ghc bug filed for this?
Apologies, but no.
I never got around to extracting a small reproduction and didn’t feel comfortable submitting a bug report to the GHC tracker without one.