Gavin Andresen - 2010-07-27 14:08:17

I've been working on adding -port= / -rpcport=  command line / config file options to bitcoin.  The idea is to let you run multiple copies of bitcoind on one machine; I need this because I'm planning on having at least two Bitcoin-related web services (the Bitcoin Faucet and a service to be named later), I want them to have completely separate wallets, but I don't want to rent multiple servers to host them.

Usage looks like this:

Satoshi pointed out that allowing bitcoin/bitcoind to run on a non-standard port could be dangerous, because if misconfigured two bitcoins might both open and write to the same database.  To prevent that, the <datadir>/db.log file is used as a lock so only one bitcoin can access the same datadir at a time (uses boost::interprocess::file_lock, which is purported to be cross-platform and well-behaved, even if bitcoin crashes).

Issues that came up as I was doing this:

I left a call to wxSingleInstanceChecker in the Windows GUI code, so no multiple-gui-bitcoins-listening-on-different-ports on Windows.  I don't do Windows...

I didn't bother making the error handling graceful if you point two bitcoins at the same datadir (you get a runtime exception "Cannot lock db.log, is bitcoin already running?").

Patches are at http://pastebin.com/2e4hfXSS; I've only tested on Linux so far, anybody willing to try this on Windows?