new(cmake,ci): added support for using jemalloc allocator instead of glibc one

[FedeDP]

What type of PR is this?

/kind feature

Any specific area of the project related to this PR?

/area build
/area CI

What this PR does / why we need it:

We never really tried different allocators, but #2495 (comment) seems to suggest that jemalloc can help us prevent memory starving the system.

Also, jemalloc allows us to customize its behavior and profile the application via malloc.conf (https://github.com/jemalloc/jemalloc/wiki/Getting-Started).
For example:

sudo MALLOC_CONF="prof:true,lg_prof_interval:30,prof_accum:false,prof_prefix:jeprof.out,prof_final:true" falco

Also, the PR adds support for jemalloc stats to stats_writer and prometheus metrics, by enabling the new config key:
metrics.jemalloc_stats_enabled: true. Disabled by default.

Example output:

falco.jemalloc.active_mb=18.3 falco.jemalloc.allocated_mb=17.2 falco.jemalloc.mapped_mb=36.9 falco.jemalloc.metadata_mb=5.7 falco.jemalloc.resident_mb=30.5 falco.jemalloc.retained_mb=28.6

Or, for prometheus:

# HELP falcosecurity_falco_jemalloc_active_bytes https://falco.org/docs/metrics/
# TYPE falcosecurity_falco_jemalloc_active_bytes counter
falcosecurity_falco_jemalloc_active_bytes 21729280.000000
# HELP falcosecurity_falco_jemalloc_allocated_bytes https://falco.org/docs/metrics/
# TYPE falcosecurity_falco_jemalloc_allocated_bytes counter
falcosecurity_falco_jemalloc_allocated_bytes 19951680.000000
# HELP falcosecurity_falco_jemalloc_mapped_bytes https://falco.org/docs/metrics/
# TYPE falcosecurity_falco_jemalloc_mapped_bytes counter
falcosecurity_falco_jemalloc_mapped_bytes 52469760.000000
# HELP falcosecurity_falco_jemalloc_metadata_bytes https://falco.org/docs/metrics/
# TYPE falcosecurity_falco_jemalloc_metadata_bytes counter
falcosecurity_falco_jemalloc_metadata_bytes 8636272.000000
# HELP falcosecurity_falco_jemalloc_metadata_thp_bytes https://falco.org/docs/metrics/
# TYPE falcosecurity_falco_jemalloc_metadata_thp_bytes counter
falcosecurity_falco_jemalloc_metadata_thp_bytes 0.000000
# HELP falcosecurity_falco_jemalloc_resident_bytes https://falco.org/docs/metrics/
# TYPE falcosecurity_falco_jemalloc_resident_bytes counter
falcosecurity_falco_jemalloc_resident_bytes 33603584.000000
# HELP falcosecurity_falco_jemalloc_retained_bytes https://falco.org/docs/metrics/
# TYPE falcosecurity_falco_jemalloc_retained_bytes counter
falcosecurity_falco_jemalloc_retained_bytes 39280640.000000
# HELP falcosecurity_falco_jemalloc_zero_reallocs_bytes https://falco.org/docs/metrics/
# TYPE falcosecurity_falco_jemalloc_zero_reallocs_bytes counter
falcosecurity_falco_jemalloc_zero_reallocs_bytes 0.000000

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

The jemalloc allocator is enabled by default for published packages.

Does this PR introduce a user-facing change?:

new(cmake,ci): added support for using jemalloc allocator instead of glibc one and use it by default for release artifacts

[poiana]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: FedeDP

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[FedeDP]

/milestone 0.40.0

[FedeDP]

All other METRICS_V2_... defines live in libs; give this a big number to avoid conflicts.

[FedeDP]

CI Build / test-dev-packages / test-packages (pull_request) Failing after 2m

There must be some issues with sanitizer + jemalloc i think :/

[FedeDP]

/cc @sgaist

[sgaist]

Seeing the comment about jemalloc and ASAN above, shouldn't there be a check done here that fails the configuration if both are enabled ? Otherwise we will likely have users that will get problematic builds.

[FedeDP]

I agree, i'll just add a warning!

[FedeDP]

Pushed!