§2025-04-27

Building MongoDB From Source

0. requirements

sudo apt-get install build-essential libcurl4-openssl-dev git

1. git clone

(PyTorch) alexlai@AgxOrin:~/build$ pwd
/home/alexlai/build
$ git clone https://github.com/mongodb/mongo.git

2. build

If I git checkout to other branch it seems will fail! I have to work on master branch

$ cd mongo 
$ python buildscripts/install_bazel.py  # <- at master branch
Downloading bazelisk...
Downloaded bazelisk to /home/alexlai/.local/bin/bazelisk
Symlinked bazel to /home/alexlai/.local/bin/bazel

(PyTorch) alexlai@AgxOrin:~/build/mongo$ which bazel
/home/alexlai/.local/bin/bazel

$ echo $PATH
/home/alexlai/.local/bin:/home/alexlai/.local/bin:/home/alexlai/anaconda3/envs/PyTorch/bin:/home/alexlai/anaconda3/condabin:/usr/local/cuda-12.6/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin

1st trial without log and from my Mac

 $ bazel build install-mongod   --cxxopt='-Wno-error'   --remote_executor=   --remote_cache=

or,

• it's compiled OK, but binary will failed on odroid-N2 with illegal instruction

$ bazel build install-mongod   --cxxopt='-Wno-error'

• still not for odrpid-n2

bazel build install-mongod \
  --cxxopt='-Wno-error' \
  --cxxopt='-march=armv8-a' \
  --cxxopt='-mtune=cortex-a73' \
  --conlyopt='-march=armv8-a' \
  --conlyopt='-mtune=cortex-a73'

• odroid-N2

– Maximum CPU clock of Quad-core Cortex-A73 is increased to 2.4Ghz from 1.8Ghz.
– Maximum CPU clock of Dual-core Cortex-A53 is increased to 2.0Ghz from 1.9Ghz.

• the followings still illegal instructions on odroid-N2

bazel build //src/mongo/db/mongod:install-mongod \
  --cxxopt='-march=armv8-a+crc' \
  --cxxopt='-mtune=cortex-a53' \
  --conlyopt='-march=armv8-a+crc' \
  --conlyopt='-mtune=cortex-a53' \
  --cxxopt='-g' \
  --strip=never

¶Where to find Binaries

The build system will produce an installation tree into bazel-bin/install, as well individual install target trees like bazel-bin/.

bazel build install-mongod \
  --cxxopt='-march=armv8.2-a+crc+crypto' \
  --cxxopt='-mtune=cortex-a73' \
  --conlyopt='-march=armv8.2-a+crc+crypto' \
  --conlyopt='-mtune=cortex-a73' \
  --cxxopt='-g' \
  --strip=never

Starting in MongoDB 8.0, MongoDB uses an upgraded version of TCMalloc that uses per-CPU caches, instead of per-thread caches, to reduce memory fragmentation and make your database more resilient to high-stress workloads.

• 1: Disable tcmalloc, MongoDB can be built without tcmalloc using this flag:
  • --use-system-allocator

bazel build install-mongod \
  --cxxopt='-mcpu=cortex-a73' \
  --conlyopt='-mcpu=cortex-a73' \
  --copt='-DUSE_SYSTEM_ALLOCATOR=1' \
  --define=use_system_allocator=true \
  --strip=never
```
    
Workaround 2: Rebuild tcmalloc With Safe Flags
If you need tcmalloc (for performance), you must force Bazel to build that target with conservative flags:

Use --per_file_copt to apply stricter flags just to tcmalloc.

Example:


--per_file_copt=src/third_party/tcmalloc/.*@-mcpu=cortex-a73
    
```
scp Agxorin.yushei.net://home/alexlai/build/mongo//bazel-bin/install/bin/mongod ./
```
    
2025-04-28
    
```
bazel clean --expunge --async
rm -rf bazel-out/*/bin/src/third_party/tcmalloc

    
```
bazel build install-mongod \
  --cxxopt='-mcpu=cortex-a73' \
  --conlyopt='-mcpu=cortex-a73' \
  --copt='-march=armv8-a' \
  --copt='-DUSE_SYSTEM_ALLOCATOR=1' \
  --define=use_system_allocator=true \
  --define=allocator=system \
  --define=tcmalloc=disabled \
  --define=jemalloc=disabled \
  --linkopt='-Wl,--no-as-needed' \
  --strip=never
```

```
bazel build install-mongod \
  --define=tcmalloc=disabled \
  --define=jemalloc=disabled \
  --linkopt='-Wl,--no-as-needed' \
  --strip=never
```

```
bazel build install-mongod \
  --cpu=arm64 \
  --copt="-march=armv8-a" \
  --copt="-mtune=cortex-a53" \
  --define=tcmalloc=disabled \
  --define=jemalloc=disabled \
  --linkopt='-Wl,--no-as-needed' \
  --strip=never
```

----

Ask deepSeek

```
bazel build --config=opt --define=use_tcmalloc=false //src/mongo/tools/installer:install-mongod
```
---

$para:2025-04-29

All the above failed to generate one for odroid-N2


- odroid-N2

– Maximum CPU clock of Quad-core Cortex-A73 is increased to 2.4Ghz from 1.8Ghz.
– Maximum CPU clock of Dual-core Cortex-A53 is increased to 2.0Ghz from 1.9Ghz.

(nnn/ 7,299)
```
bazel build \
  --config=opt \
  --define=use_tcmalloc=false \
  --cpu=arm64 \
  --crosstool_top=@bazel_tools//tools/cpp:toolchain \
  --host_crosstool_top=@bazel_tools//tools/cpp:toolchain \
  --copt=-march=armv8-a \
  --copt=-mcpu=cortex-a73 \
  --copt=-mno-outline-atomics \
  --cxxopt=-march=armv8-a \
  --cxxopt=-mcpu=cortex-a73 \
  --cxxopt=-mno-outline-atomics \
  --cxxopt=-Wno-error \
  --linkopt=-latomic \
  --disable_warnings_as_errors=True \
  install-mongod
```