| Type | Bug | Status | reviewed | Date | 11-Jul-2014 12:55 |
|---|---|---|---|---|---|
| Version | r3 master | Category | Ports | Submitted by | rebolek |
| Platform | All | Severity | major | Priority | normal |
| Summary | Non-linear performance of TCP writes |
|---|---|
| Description |
I've been testing my Redis scheme and found a strange thing when writing data to a port. When writing to the TCP port data that are smaller than 256kB, everything works just as expected and the action takes few miliseconds. However, when I hit the 256kB threshold, things are very different. See following table, to see, how much it slows down: 100'000 bytes - 0,006 sec 200'000 bytes - 0,035 sec 250'000 bytes - 0,067 sec 300'000 bytes - 0,197 sec 500'000 bytes - 0,585 sec 1'000'000 bytes - 1,618 sec 2'000'000 bytes - 3,620 sec 4'000'000 bytes - 7,687 sec @HappySpoon suggested sending data in chunks, so I switch the code to use 32'000 bytes chunk and sending even four megabyte data now take tens to few hundreds of miliseconds as expected. When using this mode, I observed that there's a delay after each eighth write, so it is probably constructing the 256kB buffer somehow internally. So I tested using 256'000 bytes buffer instead of 32'000 and found that using bigger buffer does not work, the interpreter will hang up and waits (can be interrupted with [ESC] key, however). This will happen with any size from 32'001 up. Using smaller buffer is also not an option and is even dangerous than bigger buffer. The smallest working buffer is 31'700 bytes, when using buffer of size 31'699 bytes or smaller, REBOL interpreter will crash with error #1412: REBOL System Error. So, to wrap it up somehow: 1) when writing big data (anything bigger that 256kB) to TCP, buffered writing should be used, otherwise the writing will get extremely slow, and 2) when using buffered writing, buffer must be exactly 32'000 bytes, anything bigger will hang up interpreter and anything smaller than 31'700 will crash the interpreter. |
| Example code |
| Assigned to | n/a | Fixed in | - | Last Update | 26-Jan-2015 07:36 |
|---|
| Date | User | Field | Action | Change |
|---|---|---|---|---|
| 26-Jan-2015 07:36 | abolka | Severity | Modified | minor => major |
| 26-Jan-2015 07:36 | abolka | Status | Modified | submitted => reviewed |
| 26-Jan-2015 07:36 | abolka | Type | Modified | Issue => Bug |
| 26-Jan-2015 07:35 | abolka | Summary | Modified | non linear response of the TCP write => Non-linear performance of TCP writes |
| 26-Jan-2015 07:35 | abolka | Description | Modified | - |
| 11-Jul-2014 12:55 | rebolek | Ticket | Added | - |