databases/mongodb fails to start, assertion failure in unit test

[Wesley Shields]

On Sat, Jan 26, 2013 at 07:06:21AM -0800, Waitman Gobble wrote:
> Waitman Gobble <uzimac at da3m0n8t3r.com> wrote ..
> > 
> > Hi,
> > 
> > I've installed databases/mongodb and get an error when starting.
> > 
> > # /usr/local/etc/rc.d/mongod start
> > Starting mongod.
> > forked process: 59576
> > all output going to: /var/db/mongodb/mongod.log
> > /usr/local/etc/rc.d/mongod: WARNING: failed to start mongod
> > 
> > # cat /var/db/mongodb/mongod.log
> > 
> > Fri Jan 25 00:30:57   Assertion failure l < bigl src/mongo/db/btree.cpp 1973
> > 0x5a503d 0x5eb41d 0x74dce9 0x547638 0x545ed9 0x542bc1 
> >  0x5a503d <_ZN5mongo12verifyFailedEPKcS1_j+285> at /usr/local/bin/mongod
> >  0x5eb41d <_ZN5mongo10BTUnitTest3runEv+333> at /usr/local/bin/mongod
> >  0x74dce9 <_ZN5mongo11StartupTest8runTestsEv+57> at /usr/local/bin/mongod
> >  0x547638 <main+5992> at /usr/local/bin/mongod
> >  0x545ed9 <main+9> at /usr/local/bin/mongod
> >  0x542bc1 <_start+145> at /usr/local/bin/mongod
> > Fri Jan 25 00:30:57 Got signal: 6 (Abort trap: 6).
> > 
> > 
> >     
> > # portversion -v mongodb
> > mongodb-2.2.0_1             =  up-to-date with port
> > 
> > # uname -a
> > FreeBSD kamira.waitman.net 9.1-STABLE FreeBSD 9.1-STABLE #0 r245772M: Tue Jan 22
> > 06:09:00 PST 2013     root at kamira.waitman.net:/usr/obj/usr/src/sys/BURPLEX  amd64
> > 
> >     
> > I added a couple lines to print the values before the failure.
> > 
> > 
> > src/mongo/db/btree.h
> > 
> > ..
> > 
> >     struct BTUnitTest : public StartupTest {
> >         void run() {
> >             DiskLoc big(0xf12312, 0x70001234);
> >             DiskLoc56Bit bigl;
> >             {
> >                 bigl = big;
> >                 verify( big == bigl );
> >                 DiskLoc e = bigl;
> >                 verify( big == e );
> >             }
> >             {
> >                 DiskLoc d;
> >                 verify( d.isNull() );
> >                 DiskLoc56Bit l;
> >                 l = d;
> >                 verify( l.isNull() );
> >                 d = l;
> >                 verify( d.isNull() );
> > 
> > printf("bigl %s\n",bigl.toString().c_str());
> > printf("l %s\n",l.toString().c_str());
> > 
> >                 verify( l < bigl );
> >             }
> >         }
> >     } btunittest;
> > ..
> > 
> > 
> > output:
> >    
> > bigl f12312:70001234
> > l null
> > Thu Jan 24 23:18:17   Assertion failure l < bigl src/mongo/db/btree.cpp 1978
> >    
> > 
> > looking at    
> > src/mongo/db/diskloc.h
> >    
> >     bool isNull() const { return _a == -1; }
> > ..   
> >     int compare(const DiskLoc& b) const {
> >             int x = _a - b._a;
> >             if ( x )
> >                 return x;
> >             return ofs - b.ofs;
> >         }
> >         bool operator<(const DiskLoc& b) const {
> >             return compare(b) < 0;
> >         }
> > ..
> >         void Null() {
> >             _a = -1;
> >             ofs = 0; /* note NullOfs is different. todo clean up.  see refs to
> > NullOfs in code - use is valid but outside DiskLoc context so confusing as-is.
> > */
> >         }
> > 
> > 
> >    
> > it seems that this should be working!
> > 
> > test model:
> > 
> > #include <stdio.h>
> > 
> > int
> > compare (int a, int b)
> > {
> >         int x = a - b;
> >             if ( x )
> >                 return x;
> >         return 555;
> > }
> > 
> > bool
> > ncompare (int a, int b)
> > {
> >         return compare(a,b) < 0;
> > }
> > 
> > int
> > main (void)
> > {
> >         int a, b;
> >         a = -1;
> >         b = 0xf12312;
> >         int c = a - b;
> >         printf("%d\n",c);
> >         c = compare(a,b);
> >         printf("%d\n",c);
> >         bool d = ncompare(a,b);
> >         printf("%d\n",d);
> >         bool e = ncompare(b,a);
> >         printf("%d\n",e);
> >         return 0;
> > }
> > 
> > # clang++ -o test test.cpp
> > # ./test
> > -15803155
> > -15803155
> > 1
> > 0
> > 
> > 
> > I'm missing something...
> >  
> > Suggestions, tips, hints much appreciated. 
> > 
> > Thanks,
> > 
> > -- 
> > Waitman Gobble
> > San Jose California USA
> 
> Hi,
> 
> I've tinkered around with this problem. Commenting out the 'verify( l
> < bigl );' line in src/mongo/db/btree.h solves the assertion failure
> problem, and mongodb starts and runs. However, after reviewing the
> code it seems this 'start' unit test is only actually testing if the
> thing can 'subtract integers.' I'm very puzzled as to why it is
> failing, it's bombing out when it does 'verify ((-1 - 0xf12312)<0)'.
> which seems trivial.
> 
> The code that runs the unit test/StartupTest is simple, but i haven't
> yet found the 'verify' macro, at least i believe it's a macro. 
> 
> Anyhow, commenting out the test line gets mongodb running, but I'm
> wondering what other problems there could be. (?) 
> 
> I found that compiling with base gcc avoids the startup problem, so
> this indeed seems to be an issue related to building with clang. clang
> builds mongodb without error, however running the mongodb compiled
> with clang fails during 'startuptest'. 
> 
> IMHO It would be good to track down the problem, at least understand
> the cause, but at this moment it seems like compiling mongodb with gcc
> is the way to go.
> 
> I've updated the port to use the latest release/ 2.2.2 version of
> mongodb, I'll submit a PR in a bit, (it does not appear to have been
> submitted already) maybe somebody wants to use it. (The startup
> assertion failure affects the existing port '2.2.0' as well as 2.2.2)

Please CC me on the PR as I would like to get that in the tree.

As for the clang problem, I think this might be something to take up
with the mongodb developers.

-- WXS