TLS context - unclear when used?

[asfg84]

Dear all,

when trying to figure out why the initialization of the API via initAPI(options) takes so long, I found that the call to create the Aws::Crt::Io::TlsContext context is rather slow (https://github.com/aws/aws-sdk-cpp/blob/main/src/aws-cpp-sdk-core/source/Aws.cpp#L101). When digging deeper into the code, I could not find when this TLS context will ever be used again, because it is just used to create the TLS options which are then set via SetDefaultTlsConnectionOptions (https://github.com/aws/aws-sdk-cpp/blob/main/src/aws-cpp-sdk-core/source/Aws.cpp#L103 and https://github.com/aws/aws-sdk-cpp/blob/main/src/aws-cpp-sdk-core/source/Globals.cpp#L40) and live as a static member variable g_defaultTlsConnectionOptions in Globals.cpp. The only way this variable is accessed is via GetDefaultTlsConnectionOptions() (https://github.com/aws/aws-sdk-cpp/blob/main/src/aws-cpp-sdk-core/source/Globals.cpp#L43), which is never called from inside the aws cpp sdk. So I am wondering what this is about? Is there some usage of this static member that I cannot see? To me it does not seem to make a difference when I just comment the whole TLS initialization section, except that the call to initAPI() gets much faster.

Thanks!

[jmklix]

TLS context is only used by the s3 crt client. That being said it shouldn't be taking that long to initialize it. Can you provide a quick repo and details about your environment that can help us look into this? How long exactly is this taking to initialize with and without TLS context?

[asfg84]

Sorry for the late reply. With this minimal example

  auto start = std::chrono::steady_clock::now();

  Aws::SDKOptions options;
  options.loggingOptions.logLevel = Aws::Utils::Logging::LogLevel::Info;
  Aws::InitAPI(options);

  auto dc = std::chrono::steady_clock::now() - start;
  auto ms = std::chrono::duration_cast<std::chrono::microseconds>(dc).count();

  printf("initialization runtime: %.6f ms", ms * 1e-3);

On an amd64 system with Ubuntu 22.04 I measure nearly 98ms initialization runtime with the TLS context, and around 32ms without it. (Of these 32ms, 31ms come from the initialization of the mqtt libraray, that we do not require either, see also awslabs/aws-crt-cpp#630).

The runtimes strongly depend on the system and architecture, of course. On amd64 with Ubuntu 20.04 I measure only 4ms with TLS and 2ms without, so this is no issue at all. But on armhf or amd64 and on Ubuntu 22.04 it is rather slow.