[Bug 2016845] Re: ceph should build linked with tcmalloc

[Dan Hill]

The Ceph CMake files are a bit of a tangled mess. The tcmalloc library
was originally linked through an `${ALLOC_LIBS}` definition that was
directly added to individual daemon / utility targets. Nautilus reworked
how these libraries were linked by refactoring everything into bundles
of common libraries [0].

As a result, ceph-osd links the tcmalloc library through several layers of CMake library dependencies:
> `ceph-osd` adds the `os` set of libraries
-> `os` adds the `heap_profiler` set of libraries
--> `heap_profiler` adds the `gperftools::tcmalloc` library

The core issue is that the `heap_profiler` definition removes tcmalloc
when `WITH_SEASTAR` is defined [1]. Ubuntu packaging has been built
`WITH_SEASTAR=ON` since 16.2.4-0ubuntu1 [2].

More recently, upstream also broke tcmalloc while enabling seastar. They
have proposed a solution that switches back to linking individual
targets with `${ALLOC_LIBS}` [3]. This fix has been merged into master,
with backports to quincy and pacific in progress [4].

[0] https://github.com/ceph/ceph/pull/22990/commits/2e012870315e5a08e90c27f14666e8518b94caef
[1] https://github.com/ceph/ceph/commit/028159ef6ea0f43c4eaf2314d7d73f92bbc5bd99
[2] https://bugs.launchpad.net/ubuntu/+source/ceph/+bug/1928645
[3] https://github.com/ceph/ceph/pull/46103/commits/1e3d2b53cfeeff4bac2f384c6445b65eb9e8396f
[4] https://tracker.ceph.com/issues/55519


** Bug watch added: tracker.ceph.com/issues #55519
   http://tracker.ceph.com/issues/55519

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https://bugs.launchpad.net/bugs/2016845

Title:
  ceph should build linked with tcmalloc

Status in ceph package in Ubuntu:
  Confirmed

Bug description:
  Sometime between 15.2.17 on focal and 17.2.5 on either focal via the
  Yoga UCA or on Jammy the ceph-osd process stopped linking to tcmalloc.
  tcmalloc should continue to be enabled for ceph performance

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