Uploaded function has a 50/50 chance to succeed.

[aksir1987]

Hello,

Fantastic sdk and very much needed.

Recently I followed the basic tutorial and run a simple C++ program on aws lambda.

However, it has a 50/50 chance of success, which is very confusing.

It is a simple program with little usage of dynamic memory allocation and only printf and std::string is used from the standard library.

When it failed, it returns
{
"errorMessage": "RequestId: da9a1e36-07cb-45a2-9e4e-db2f80288d11 Process exited before completing request"
}

The printf marks I put there indicates the code went through just fine but it failed to get out of the handler function.

What can be the issue?

Thank you.

[marcomagdy]

Can you provide the code here to reproduce the problem?

[phadej]

Do you have your lambda's network configured right, if you configure other of your VPC subnets wrong (you need two!) then lambda will work 50% of the time.

[aksir1987]

Can you provide the code here to reproduce the problem?

The total code is a bit difficult to show here due to the length. Here is the basic content.

Everything inside Cmyclass is standard C++ and thoroughly tested.

invocation_response my_handler(invocation_request const& request)
{

Cmyclass *pmyclass= new Cmyclass;

std::string str  = pmyclass->get_str();

delete pmyclass;

printf("Sucess\n");

return invocation_response::success(str, "application/json");
}

In the test function on the page of aws-lambda, it shows me:

START RequestId: 1b475a69-f9a9-4b13-8b45-aca566c7ecc8 Version: $LATEST
Sucess
[ERROR] [1552062898632] LAMBDA_RUNTIME Failed to get next invocation. No Response from endpoint
END RequestId: 1b475a69-f9a9-4b13-8b45-aca566c7ecc8
REPORT RequestId: 1b475a69-f9a9-4b13-8b45-aca566c7ecc8 Duration: 130.08 ms Billed Duration: 200 ms Memory Size: 128 MB Max Memory Used: 104 MB
RequestId: 1b475a69-f9a9-4b13-8b45-aca566c7ecc8 Process exited before completing request

So the typoed "Sucess" indicate that the myclass method has gone through with no problem, correct?
What is the problem then?

[aksir1987]

Do you have your lambda's network configured right, if you configure other of your VPC subnets wrong (you need two!) then lambda will work 50% of the time.

I chose no VPC by default for just trying this. Basically all the configurations are default.

Is one required to run smoothly?

[marcomagdy]

So the typoed "Sucess" indicate that the myclass method has gone through with no problem, correct?

The code you pasted above seems fine.
However, if str was a reference as in std::string& str = pmyclass->get_str(); then that would explain why you're crashing sometimes.

[aksir1987]

So the typoed "Sucess" indicate that the myclass method has gone through with no problem, correct?

The code you pasted above seems fine.
However, if str was a reference as in std::string& str = pmyclass->get_str(); then that would explain why you're crashing sometimes.

No it is not . get_str() is a std::string get_str() and every time it did print out "Sucess".

[marcomagdy]

I didn't mean the signature of get_str().
I'm saying the variable you're assigning the result of that method to.
std::string& a = p->get_str(); vs std::string b = p->get_str();

In the case of (a) it's a dangling reference if you delete p.
In the case of (b) it's fine.

[aksir1987]

I didn't mean the signature of get_str().
I'm saying the variable you're assigning the result of that method to.
std::string& a = p->get_str(); vs std::string b = p->get_str();

In the case of (a) it's a dangling reference if you delete p.
In the case of (b) it's fine.

I am pretty sure it is (b). Yet it still crash...