WSL2 io speeds on Linux filesystem are slow

Question

Trying out WSL2 for the first time. Running Ubuntu 18.04 on a Dell Latitude 9510 with an SSD. Noticed build speeds of a React project were brutally slow. Per all the articles on the web I'm running the project out of ~ and not the windows mount. Ran a benchmark using sysbench --test=fileio --file-test-mode=seqwr run in ~ and got:

File operations:
    reads/s:                      0.00
    writes/s:                     3009.34
    fsyncs/s:                     3841.15

Throughput:
    read, MiB/s:                  0.00
    written, MiB/s:               47.02

General statistics:
    total time:                          10.0002s
    total number of events:              68520

Latency (ms):
         min:                                  0.01
         avg:                                  0.14
         max:                                 22.55
         95th percentile:                      0.31
         sum:                               9927.40

Threads fairness:
    events (avg/stddev):           68520.0000/0.00
    execution time (avg/stddev):   9.9274/0.00

If I'm reading this correctly, that wrote 47 mb/s. Ran the same test on my mac mini and got 942 mb/s. Is this normal? This seems like the Linux i/o speeds on WSL are unusably slow. Any thoughts on ways to speed this up?

---edit--- Not sure if this is a fair comparison, but the output of winsat disk -drive c on the same machine from the Windows side. Smoking fast:

> Dshow Video Encode Time                      0.00000 s
> Dshow Video Decode Time                      0.00000 s
> Media Foundation Decode Time                 0.00000 s
> Disk  Random 16.0 Read                       719.55 MB/s          8.5
> Disk  Sequential 64.0 Read                   1940.39 MB/s          9.0
> Disk  Sequential 64.0 Write                  1239.84 MB/s          8.6
> Average Read Time with Sequential Writes     0.077 ms          8.8
> Latency: 95th Percentile                     0.219 ms          8.9
> Latency: Maximum                             2.561 ms          8.7
> Average Read Time with Random Writes         0.080 ms          8.9
> Total Run Time 00:00:07.55

---edit 2--- Windows version: Windows 10 Pro, Version 20H2 Build 19042

Answer 1

Late answer, but I had the same issue and wanted to post my solution for anyone who has the problem:

Windows Defender seems to destroy the read speeds in WSL. I added the entire rootfs folder as an exclusion. If you're comfortable turning off Windows Defender, I recommend that as well. Any antivirus probably has similar issues, so adding the WSL directories as an exclusion is probably you best bet.

Answer 2

You are modifying a class/static variable and not a state variable. Class variables are shared across all instances of the same class. Instance variables need to set to the self property.

As stated by @BatWannaBe and @WonderCricket, When you modified the string class variable, you removed that instance's reference to the original class property. Modifying the dictionary required accessing the property and modifying its internal state, but the root reference to the same dictionary was not changed.

class Apple:
  def __init__(self):
    self.prop = { 'color': 'red' }   
    self.color2 = 'red'


a1 = Apple()
a2 = Apple()

a1.prop['color'] = 'blue'
a1.color2 = 'blue'

print(a1.prop, a1.color2)
print(a2.prop, a2.color2)