Concurrency issue in NetworkingModule causes _STL_VERIFY to fail

[lamxdoan]

Environment

If you are using latest version:

1. react-native -v:
   react-native-cli: 2.0.1
   react-native: 0.60.6
2. react-native run-windows --info:
   System:
   OS: Windows 10 10.0.18363
   CPU: (12) x64 Intel(R) Xeon(R) CPU E5-1650 v4 @ 3.60GHz
   Memory: 12.28 GB / 31.92 GB
   Binaries:
   Node: 11.3.0 - C:\Program Files\nodejs\node.EXE
   Yarn: 1.16.0 - C:\Program Files (x86)\Yarn\bin\yarn.CMD
   npm: 6.4.1 - C:\Program Files\nodejs\npm.CMD
   npmPackages:
   react: 16.8.6 => 16.8.6
   react-native: 0.60.6 => 0.60.6
   react-native-windows: 0.60.0-vnext.141 => 0.60.0-vnext.141
   rnpm-plugin-windows: 0.3.5 => 0.3.5
   Installed UWP SDKs:
   10.0.16299.0
   10.0.17134.0
   10.0.17749.0
   10.0.17763.0
   10.0.18362.0

Then, specify:

• Target Platform Version(s): 10.0.18362.0

• Target Device(s): Desktop

• Visual Studio Version: 2017

• Build Configuration: Debug

Steps to Reproduce

1. In RNW app, make a large number of network requests so that NetworkModule.cpp gets hammered. (We use axios and we see this issue often after we kick off 800+ requests)

Expected Behavior

No _STL_VERIFY asserts get hit.

Actual Behavior

STL_VERIFY asserts get hit and the app is forced to close.

Additional context

(Write any other additional context that may help in root causing the issue.)

The issue is that the large number of requests increases the chances that m_requests map gets modified while an add or erase is being done which causes the iterators to be invalidated.

[lamxdoan]

I have a fix for this that adds locking around m_requests map.