get_utxos() is called pretty often, both spuriously, and on focus change, on tab switch, &c. It blocks as it iterates, functionally, /every/ address the wallet knows of. On large wallets (like testnet vpub5VfkVzoT7qgd5gUKjxgGE2oMJU4zKSktusfLx2NaQCTfSeeSY3S723qXKUZZaJzaF6YaF8nwQgbMTWx54Ugkf4NZvSxdzicENHoLJh96EKg from #6625 with 11k TXes and 10.5k addresses), this takes 1.3s of 100%ed CPU usage, basically in a loop from the UI thread. get_utxos() is 50-70% of the flame-graph when sampling a synced wallet process. This data is a function of the block-chain state, and we have hooks that notify us of when the block-chain state changes: we can just cache the result and only re-compute it then. For example, here's a trace log where get_utxos() has print(end - start, len(domain), block_height) and a transaction is clearing: 1.3775344607420266 10540 4507192 0.0010390589013695717 10540 4507192 cached! 0.001393263228237629 10540 4507192 cached! 0.0009001069702208042 10540 4507192 cached! 0.0010241391137242317 10540 4507192 cached! ... 0.00207632128149271 10540 4507192 cached! 0.001397700048983097 10540 4507192 cached! invalidate_cache 1.4686454269103706 10540 4507192 0.0012429207563400269 10540 4507192 cached! 0.0015075239352881908 10540 4507192 cached! 0.0010459059849381447 10540 4507192 cached! 0.0009669591672718525 10540 4507192 cached! ... on_event_blockchain_updated invalidate_cache 1.3897203942760825 10540 4507193 0.0010689008049666882 10540 4507193 cached! 0.0010420521721243858 10540 4507193 cached! ... invalidate_cache 1.408584670163691 10540 4507193 0.001336586195975542 10540 4507193 cached! 0.0009196233004331589 10540 4507193 cached! 0.0009176661260426044 10540 4507193 cached! ... about 30s of low activity. Without this patch, the UI is prone to freezing, running behind, and I wouldn't be surprised if UI thread blocking on Windows ends up crashing to some extent as the issue notes. In the log, this manifests as a much slower but consistent stream of full 1.3-1.4s updates during use, and every time the window is focused.
Electrum - Lightweight Bitcoin client
Licence: MIT Licence
Author: Thomas Voegtlin
Language: Python (>= 3.10)
Homepage: https://electrum.org/
Getting started
(If you've come here looking to simply run Electrum, you may download it here.)
Electrum itself is pure Python, and so are most of the required dependencies, but not everything. The following sections describe how to run from source, but here is a TL;DR:
$ sudo apt-get install libsecp256k1-dev
$ ELECTRUM_ECC_DONT_COMPILE=1 python3 -m pip install --user ".[gui,crypto]"
Not pure-python dependencies
Qt GUI
If you want to use the Qt interface, install the Qt dependencies:
$ sudo apt-get install python3-pyqt6
libsecp256k1
For elliptic curve operations, libsecp256k1 is a required dependency.
If you "pip install" Electrum, by default libsecp will get compiled locally,
as part of the electrum-ecc dependency. This can be opted-out of,
by setting the ELECTRUM_ECC_DONT_COMPILE=1 environment variable.
For the compilation to work, besides a C compiler, you need at least:
$ sudo apt-get install automake libtool
If you opt out of the compilation, you need to provide libsecp in another way, e.g.:
$ sudo apt-get install libsecp256k1-dev
cryptography
Due to the need for fast symmetric ciphers, cryptography is required. Install from your package manager (or from pip):
$ sudo apt-get install python3-cryptography
hardware-wallet support
If you would like hardware wallet support, see this.
Running from tar.gz
If you downloaded the official package (tar.gz), you can run Electrum from its root directory without installing it on your system; all the pure python dependencies are included in the 'packages' directory. To run Electrum from its root directory, just do:
$ ./run_electrum
You can also install Electrum on your system, by running this command:
$ sudo apt-get install python3-setuptools python3-pip
$ python3 -m pip install --user .
This will download and install the Python dependencies used by
Electrum instead of using the 'packages' directory.
It will also place an executable named electrum in ~/.local/bin,
so make sure that is on your PATH variable.
Development version (git clone)
(For OS-specific instructions, see here for Windows, and for macOS)
Check out the code from GitHub:
$ git clone https://github.com/spesmilo/electrum.git
$ cd electrum
$ git submodule update --init
Run install (this should install dependencies):
$ python3 -m pip install --user -e .
Create translations (optional):
$ sudo apt-get install gettext
$ ./contrib/locale/build_locale.sh electrum/locale/locale electrum/locale/locale
Finally, to start Electrum:
$ ./run_electrum
Run tests
Run unit tests with pytest:
$ pytest tests -v
To run a single file, specify it directly like this:
$ pytest tests/test_bitcoin.py -v
Creating Binaries
Contributing
Any help testing the software, reporting or fixing bugs, reviewing pull requests and recent changes, writing tests, or helping with outstanding issues is very welcome. Implementing new features, or improving/refactoring the codebase, is of course also welcome, but to avoid wasted effort, especially for larger changes, we encourage discussing these on the issue tracker or IRC first.
Besides GitHub,
most communication about Electrum development happens on IRC, in the
#electrum channel on Libera Chat. The easiest way to participate on IRC is
with the web client, web.libera.chat.
Please improve translations on Crowdin.