It’s been quite a while, but Alys 0.2.0 is now released! There are quite a few highlights:
MessagePack traces
The .alys format is now based on MessagePack. This can result in
massive decreases in file size, largely thanks to variable-length
integer encoding.
Sampled events via ALYS_SAMPLE_INTERVAL
On large applications, writing an event on every single allocation is
slow and can result in massive, hard-to-inspect trace files. Now, you
can set ALYS_SAMPLE_INTERVAL=bytes:N to only write events for every
N bytes allocated, trading granularity for significantly better
performance and a smaller file size.
PIE executable support for address-only backtraces (ELF only)
On systems that use ELF binaries, address-only backtraces will now embed
information in the trace file that allows alys_converter to symbolize
them regardless of the executable’s base address. (Support for
macOS/Mach-O will come in the future.)
Significant alys_converter performance improvements
alys_converter now uses a single llvm-symbolizer process for all
its symbolization, which can result in performance improvements of over
8x.
Flamegraphs (and folded stacks)
alys_converter can now output folded stacks (primarily used for
feeding into various flamegraph tools) and flamegraphs
(via inferno-flamegraph).
Here’s a screenshot of a flamegraph taken from running the lucky website with a sample interval of 4KiB:
ALYS_BACKTRACE_TYPE=addr is the default (ELF only)
Thanks to all of the above changes, making alys_converter
significantly faster and usable with PIE binaries,
ALYS_BACKTRACE_TYPE=addr is now the default trace type on ELF systems.
The main advantages are the smaller perf hit and trace file size, as
well as alys_converter’s symbolization giving significantly better
results.