Pending tx out of sync with blocks

Technical Issue Reporting
#1

I tried to catch all pending tx hashes and then find them inside new blocks. But it has some sync issue. Here is my simplified code example:

const provider = new ethers.providers.WebSocketProvider(
  process.env.PROVIDER_WS_URL
);

const txs = new Map();

provider.on("pending", (hash) => {
  txs.set(hash, Date.now());
});

provider.on("block", (blockNum) => {
  provider.getBlock(blockNum).then((block) => {
    const lastTx = block.transactions.pop();
    // Expected to find block tx inside previousle recorded pending txs
    console.log(block.number, lastTx, txs.get(lastTx));
  });
});
#2

what exactly is not working as expected?
on what chain are you trying to do this?

#3

It is BSC chain. I expect tx first appear in “pending” listener, and then later in “block” listener, as one of block’s transactions.

#4

but at least some of the pending transactions appear later in the new blocks? maybe some pending transactions don’t get processed right away

#5

Your are right, some pended transactions can be skipped and not get included into block. But I found opposite case, when not all transactions, included in block were pended before. Here is example:

const txs = new Map();

provider.on("pending", (hash) => {
  txs.set(hash, Date.now());
});

provider.on("block", (blockNum) => {
  provider.getBlock(blockNum).then((block) => {
    const pended = block.transactions.filter((hash) => txs.has(hash));
    console.log("New block %s", block.number);
    console.log("Total transactions: %s", block.transactions.length);
    console.log("Pended transactions: %s", pended.length);
  });
});

Here Total transaction are always greater than Pended transactions.

New block 13439924
Total transactions: 334
Pended transactions: 322
New block 13439925
Total transactions: 384
Pended transactions: 376

#6

a block has transactions collected from everywhere, maybe our speedy nodes didn’t receive all the pending transactions from everywhere

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