Build mongo 3.2.x on ARM (armv7l/arm64/aarch64) - segmentation fault

[TomFreudenberg]

While the mongod (DB) is running well after build without seen issues yet, it is not possible to get a running mongo shell [with or without javascript (mozjs) support enabled] after build.

Simple build:

mkdir -p /tmp/mongo-build

cd /tmp/mongo-build

git clone --branch "r3.2.6" --depth 1 https://github.com/mongodb/mongo.git

cd mongo

scons --disable-warnings-as-errors --prefix=/tmp/mongo-build/mongo --js-engine=mozjs mongo mongod

Even that this build will be run on all tested platforms and architectures (Linux on armv7l, aarch64, amd64) without issues during compiling, the results in case of running programs differs.

Running mongo command after build on amd64:

Just run mongo shell and try to connect to a non existing instance

./mongo mongodb://localhost:5002/sample

this will give this output:

MongoDB shell version: 3.2.6
connecting to: mongodb://localhost:5002/sample
2016-07-05T14:10:23.772+0200 W NETWORK  [thread1] Failed to connect to 127.0.0.1:5002, reason: errno:111 Connection refused
2016-07-05T14:10:23.772+0200 E QUERY    [thread1] Error: couldn't connect to server localhost:5002, connection attempt failed :
connect@src/mongo/shell/mongo.js:223:14
@(connect):1:6

exception: connect failed

Running mongo command after build on aarch64/armv7l:

Instead of this, the output on ARMs is just:

MongoDB shell version: 3.2.6
Segmentation fault (core dumped)

It seems to me that the TCP connection part might bring up that "SEGMENTATION FAULT" but I can't debug this.

I would be happy about any help to get this run.

[cyphernix]

Hello Tom

Please can you post the output of the segmentation fault by typing dmesgor sudo dmesg after you have tried to run ./mongo mongodb://localhost:5002/sample command.

Regards Keith

[TomFreudenberg]

Attached you find also the core dump from running mongo

core.zip

This was done on linaro cluster / arm64 (aarch64)

[cyphernix]

Thanks Tom much appreciated. Just another thing if you could. Would you mind running the same command with trace ./mongo mongodb://localhost:5002/sample Then post output for me.

If it's too much to copy paste then just run it like this... trace ./mongo mongodb://localhost:5002/sample > tracer

[TomFreudenberg]

Hopefully output of strace is what you mean?

strace.txt

[TomFreudenberg]

Yes it does but mongo still seg fault. New trace attached.

strace2.txt

[cyphernix]

Yeah I see it's still dying out at the same place unable to get any of those threads going. Perhaps repeat that command but pass --64bit on to it. In case it is not detecting it correctly since it's an Arm64 processor.

scons --64bit --disable-warnings-as-errors --prefix=/tmp/mongo-build/mongo --js-engine=mozjs core

[TomFreudenberg]

Hi Keith @cyphernix

there is no option --64 or --64bit. I checked the SConstruct options and get some settings for 3rdparty libraries like google-perf (tcmalloc) etc.

I do now a fresh 3.3.9 build while replacing most of the included 3rdparty libraries by system ones. I will post an update when compile is done.

[cyphernix]

Sounds like a plan. Hard to diagnose this as I don't have any device with that Architecture near me at the moment so working blind. Sorry for the back and fourth mate.

[TomFreudenberg]

Well after running a number of builds and checks, I switched into mongo release branch r3.3.9.

Doing the same build as always, this release seems to work on (at least) arm64.

I will run a check if this is ok for armv7 as well.

Attention: Target needs to be core for r3.3.x, mongo or mongod don't exist (anymore)

[TomFreudenberg]

Hi @benjamn

will it be possible to change the mongo release to at least r3.3.9 instead of r3.2.6

https://github.com/meteor/meteor/blob/release-1.4/scripts/build-dev-bundle-common.sh#L8

r3.2.6 seems not to work (mongo shell) for ARM but >r3.3.9

Thanks for a short note Tom

[TomFreudenberg]

@benjamn - sorry for silly question - r3.3.9 is still development - so I am trying to check r3.2.8

[TomFreudenberg]

OMG 👎 r3.2.8 has still Seg Fault

I will check from r3.3.0 up to r3.3.9 if possible to locate the fix

---

Update:

r3.3.0 up to r3.3.4 still Seg Fault r3.3.5 unsupported architecture arm64 r3.3.6 up to r3.3.8 fail with backtrace r3.3.9 is (the only) working release

Hopefully the issue is addressed by a small changset

[cyphernix]

Hey Tom have you read this MongoDB ticket... https://jira.mongodb.org/browse/SERVER-23126

[cyphernix]

If you issue ./mongo --help the binary works but the connection has issues dealing with a non existant database. Seg Faulting instead of failing gracefully at the non existant database.

The offending code is in /home/keith-testing/mongodb-src-r3.2.8/src/mongo/client/mongo_uri_connect.cpp

    if (!_user.empty()) {
        ret->auth(_makeAuthObjFromOptions(ret->getMaxWireVersion()));
    }
    return ret;
}

[TomFreudenberg]

Hey @cyphernix I have checked the hash but all is already applied to r3.2.8.

Still Seg Fault - it seems that just r3.3.9 is running - see comment before, up to r3.3.8 none works.

[cyphernix]

Ah yes I see what you mean so it's affected from r3.2.8 until 3.3.8. Just check that and see they have added this to it.

ret = _connectString.connect(errmsg, socketTimeout);

[TomFreudenberg]

Hey @cyphernix Keith

As you can read above, r3.3.9 is the one is running - all releases before have seg fault issue.

I will do a compare but maybe this is a huge changeset :-(

[cyphernix]

Perhaps just including the fix from 3.3.9 in mongo_uri_connect.cpp and apply it to one of the older versions will be easier? That I will leave up to you to decide. Although I'm glad we both finally managed to get to the bottom of this issue... :-)

[TomFreudenberg]

Can you post the lines please - which fix do mean?

This is the complete changeset - https://github.com/mongodb/mongo/compare/r3.3.8...r3.3.9

[cyphernix]

On the server run this command.

diff /home/mongo-3.3.9/src/mongo/client/mongo_uri_connect.cpp /home/keith-testing/mongodb-src-r3.2.8/src/mongo/client/mongo_uri_connect.cpp You will see the problem code there.