#22189 Include `hdrhistogram` as a default dependency, for `[stats].log` Issue created by huonw Is your feature request related to a problem? Please describe. Pants has support for tracking "histograms" of metrics, for instance:

Summary of `local_store_read_blob_size` observation histogram:
    min: 1
    max: 4317183
    mean: 25249.341
    std dev: 158077.770
    total observations: 863
    sum: 21790181
    p25: 368
    p50: 1870
    p75: 8959
    p90: 44191
    p95: 110527
    p99: 337919

These are shown by the

[stats]

subsystem, when

[stats].log = true

, but require the

hdrhistogram

package to be installed. If

[stats].log = true

and that package isn't installed, Pants emits a warning:

`` Please run with

--plugins=hdrhistogram

if you would like histogram summaries to be shown at the end of the run, or permanently add

[GLOBAL].plugins = ['hdrhistogram']

. This will cause Pants to install the

hdrhistogram

dependency from PyPI. ``

The warning can be silenced either with

[GLOBAL].ignore_warnings

(if the user doesn't want to install the extra package), or by ... following the instructions: [GLOBAL] ... plugins = ['hdrhistogram'] ... [stats] log = true Describe the solution you'd like Include the

hdrhistogram

package unconditionally, and thus avoid needing to encourage users to install it. This introduces (pinned) versions of two new dependencies:

hdrhistogram

itself and its transitive dependency

pbr

, which total about ~1 MB uncompressed. Given we now package Pants as a PEX with all deps included, this doesn't seem like a major problem. There's always legimatinate concerns about introducing new dependencies / having "too many dependencies", but in this case

hdrhistogram

is already an optional dependency (although I think this relationship is not currently explicitly specified in metadata anywhere), we're not introducing new load. NB. as a side benefit, doing this reduces scope for supply chain attacks on Pants installs, because we won't be encouraging users to do unpinned installs of packages from PyPI (which is what

[GLOBAL].plugins = ['hdrhistogram']

means). See also #20166. Describe alternatives you've considered • Reimplementing the histogram tracking support to avoid

hdrhistogram

(e.g. as new code in the Pants repo, or shifting all logic to Rust code): this may be a sensible longer-term improvement, but doesn't seem like it should block the short-term improvement. Additional context Discussed in https://pantsbuild.slack.com/archives/C046T6T9U/p1744381091598199?thread_ts=1744347143.246149&cid=C046T6T9U pantsbuild/pants