Long story short I am curious how a contract stores variables in memory, so is it possible to spam say 100 transactions at once and the values to be changed afterwards...I am sure I am giving bad description so here is the code to better illustrate my point:
contract thiscontract
{
uint256 balancer = 3000;
function something() public payable
{
if(balancer > 0)
{
balancer -= 1000;
msg.sender.transfer(1000);
//event Transfer(msg.sender, balancer);
}
}
}
Basically: The function should send no more than 3000 wei, each time sending 1000 wei - if 4th msg.sender calls it after the first 3 calls it will not send anything since the value is 0 and the "if" statement prevents it.
But what will happen if 100 or more transactions call the "if" simultaneously? Does the contract 'freeze' and processes every single check one after another? Or does the contract allow some sort of parallelism like a web server and many people can call it and do this exact operation in parallel?
Because if the case is as described in "parallel" what happens is:
// it takes 0.05 seconds or so to check "if" statement... // however 10000000 calls are made to cause denial of service/parallel check:
if (balancer > 0)
// let's say 5000 pass the check and continue to sending... If someone calls it an hour later it will surely fail but still way many succeed.
I am sure this isn't possible, the only thing I know is "if" check or "Require" takes some computational time and you can read a contract without any blockchain interaction, however this is so basic that it can't be possible. Maybe someone should send 200 transactions via loop statement in web3 js/python on ropsten and see if they all obey the if rule above or more succeed or better yet pass them to aws instances who execute transactions in parallel.
Final note for now: From purely programming point of view this may be impossible since the transaction will be sent to bytecode assembly LIFO which will obey the "last in, first out" rule causing indeed freeze/slowdown and impossibility of parallel execution (so no: solidity seems far simpler than java/c# or webservers with asynchronous calls and so on). I am not 100% sure and maybe the many nodes can make it possible but I admit I have limited understanding of how exactly the transaction flow occurs between Ethereum nodes.
