BUG: std::bad_alloc during mamba_read_json is silently swallowed, yielding a poisoned .solv cache and false PackagesNotFoundError.

[nikitakuklev]

Troubleshooting docs

• My problem is not solved in the Troubleshooting docs

Anaconda default channels

• I do NOT use the Anaconda default channels (pkgs/* etc.)

How did you install Mamba?

Mambaforge or latest Miniforge

Search tried in issue tracker

memory bad_alloc

Latest version of Mamba

• My problem is not solved with the latest version

Tried in Conda?

I do not have this problem with Conda, just with Mamba

Describe your issue

(disclaimer: LLM-assisted debugging - it was quite a feat to trace down)

Environment:
mamba / libmamba version: 2.5.0 (linux-64)
OS: Alma linux 9.7, Kernel 5.14.0, glibc 2.34

Description:
When evaluating repodata inside VM with overcommitted RAM, simdjson encounters a std::bad_alloc during the operator new call for parsing the json file, because the cumulative process memory exceeds the free memory.

Instead of terminating the application with a fatal Out-Of-Memory error, libmamba's exception handler catches the std::bad_alloc, abandons the JSON parse, and writes a structurally valid but entirely empty 279-byte .solv to pkgs_dirs/cache.

The SAT solver subsequently reads this empty file and outputs PackagesNotFoundError: does not exist. So you get crazy errors like 'python not found'. The user is given no indication that a memory fault occurred, and the local cache is poisoned.

GDB Backtrace:

Thread 1 "mamba" hit Catchpoint 1 (exception thrown), __cxxabiv1::__cxa_throw (obj=0x5555558a9be0, tinfo=0x7ffff7928b38 <typeinfo for std::bad_alloc>, dest=0x7ffff7779360 <std::bad_alloc::~bad_alloc()>)
#0  __cxxabiv1::__cxa_throw (...) at ../../../../libstdc++-v3/libsupc++/eh_throw.cc:80
#1  0x00007ffff77686a2 in operator new (sz=655064704) at ../../../../libstdc++-v3/libsupc++/new_op.cc:54
#2  0x00007ffff7c270e8 in mamba::solver::libsolv::mamba_read_json(...)
#3  0x00007ffff7bf11af in mamba::solver::libsolv::Database::add_repo_from_repodata_json(...)

Expected Behavior:
If mamba_read_json encounters a std::bad_alloc, the package manager must abort the transaction immediately, exit with a non-zero status code, and surface the memory allocation error to stderr. It must never commit an empty array to the .solv cache.

mamba info / micromamba info

libmamba version : 2.5.0
          mamba version : 2.5.0
           curl version : libcurl/8.18.0 OpenSSL/3.6.1 zlib/1.3.1 zstd/1.5.7 libssh2/1.11.1 nghttp2/1.67.0 mit-krb5/1.21.3
     libarchive version : libarchive 3.8.5 zlib/1.3.1 liblzma/5.8.2 bz2lib/1.0.8 liblz4/1.10.0 libzstd/1.5.7 liblzo2/2.10 openssl/3.5.4 libb2/bundled
       envs directories : /export/<>/share/miniforge3/envs
          package cache : /export/<>/share/tmp/conda_pkgs
            environment : base (active)
           env location : /export/<>/share/miniforge3
      user config files : /export/<>/.mambarc
 populated config files : /export/<>/.condarc
                          /export/<>/share/miniforge3/.condarc
       virtual packages : __unix=0=0
                          __linux=5.14.0=0
                          __glibc=2.34=0
                          __archspec=1=x86_64_v4
               channels : https://conda.anaconda.org/conda-forge/linux-64
                          https://conda.anaconda.org/conda-forge/noarch
       base environment : /export/<>/share/miniforge3
               platform : linux-64