Does anyone know how events emitted from a contract?

I can't seem to find an authoritative answer while googling and I am kind of worried that they are synchronous.

1 Answer 1


Events are emitted when a transaction is mined into a block, in the order they are fired.

When watching a pending transaction, this suggests that filters are only notified of all events when the transaction is completed, but the order of events is preserved.

When [events] are called they cause the arguments to be stored in the transaction’s log - a special data structure in the blockchain. These logs are associated with the address of the contract and will be incorporated into the blockchain...

  • 1
    Ok, that clarifies some things. But what happens to the execution of a miner if its transaction log runs out of disk or takes a really long time to complete? Will this miner effectively block the execution for the entire network?
    – Daniel
    Commented May 16, 2016 at 8:11
  • Each log costs gas and ultimately limited by the block gas limit so they are no problem for miners to handle.
    – eth
    Commented May 16, 2016 at 8:19
  • 1
    @Daniel If a miner runs out of disk, it won't successfully mine the block, so some other node will. Commented May 16, 2016 at 9:37

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