gRPC - node.js simultaneous client calls - reverse ordered

[vijeth AG]

Hi,

I have started exploring gRPC with Node.js, by basic hello world level client-server js.

Code gist snippets and outputs below.

I have noticed a strange thing If I instantiate a client and call remote function 3/4 times simultaneously, the responses of the calls are printed in reverse order - Last called rpc prints out first.

Hello.proto

https://gist.github.com/vijeth-ag/706bb09d9b5e21b29a780ebb355d56ed

server.js

https://gist.github.com/vijeth-ag/db97b6cacf7e07d3709d4edb2ecb6c29

client.js

https://gist.github.com/vijeth-ag/0affe7b04d10b0e0d1cd4771abc16b99

Actual output: on running client.js

3  Sayhello: Hello 3
2  Sayhello: Hello 2
1  Sayhello: Hello 1

I was expecting in the order 1,2,3

Also debugged server.js - the first value received in sayHelloFunction is 3.

I if I add delay in between call works in the order 1,2,3 as expected.

Please Im curious what am I missing. 

Thanks in advance

[Michael Lumish]

Those requests all happen independently. We don't make any guarantees about their order, so the library internals are free to reorder them before sending them out. In this case, the first requests you make after you construct the client object cause it to start connecting, so those requests will be queued before sending them out, making them more likely to be reordered.

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[vijeth AG]

So on the 1st call, while connection is in progress, any subsequent client calls made are stacked up. once the connection is established the call stack is resolved.

Just to validate: I made 3 calls after a 1st init call gets resolved as in code below.  Prints in the order of 1,2,3 

Thanks for your reply.

client.sayHello({name: "init"}, function(err, response) {

console.log('init complete', response.message);

client.sayHello({name: "1"}, function(err, response) {

console.log('1 Sayhello:', response.message);

});

client.sayHello({name: "2"}, function(err, response) {

console.log('2 Sayhello:', response.message);

});

client.sayHello({name: "3"}, function(err, response) {

console.log('3 Sayhello:', response.message);

});

});

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Regards

vijeth

+91-9620962446

[Michael Lumish]

I just want to make sure it's clear that the ordering behavior you have observed here is not guaranteed. Requests made before a connection is established are not necessarily reversed, the connection state internally may change after a connection is established, and requests on the same client may even get sent to different servers, making their order completely independent.

[vijeth AG]

Gotit. Thanks

--

Regards

vijeth

+91-9620962446