EXC_BAD_ACCESS on ROCKSDB_LITE, iOS Simulator #325

semireg · 2014-09-30T20:11:38Z

I'm testing RocksDB on iOS and a simple test app is crashing on simple iteration.

std::string kDBPath = "/tmp/rocksdb_simple_example";

+(void)internalIterationTest
{
    DB* db;
    Options options;

    // Optimize RocksDB. This is the easiest way to get RocksDB to perform well
//    options.IncreaseParallelism();
//    options.OptimizeLevelStyleCompaction();
    // create the DB if it's not already present
    options.create_if_missing = true;
    options.paranoid_checks = true;

    // open DB
    Status s = DB::Open(options, kDBPath, &db);
    assert(s.ok());

    // Put key-value
    s = db->Put(WriteOptions(), "key", "super duper");
    assert(s.ok());
    std::string value;
    // get value
    s = db->Get(ReadOptions(), "key", &value);
    assert(s.ok());
    assert(value == "super duper");

    NSLog(@"value:%s", value.c_str());

    ReadOptions readOptions = ReadOptions();
    readOptions.fill_cache = false;
    readOptions.snapshot = db->GetSnapshot();

    rocksdb::Iterator* it = db->NewIterator(readOptions);
    for (it->SeekToFirst();   // <---- CRASHES HERE
         it->Valid();
         it->Next()) {
        NSLog(@"key:%s value:%s", it->key().ToString().c_str(), it->value().ToString().c_str());
    }

    assert(it->status().ok()); // Check for any errors found during the scan
    delete it;
    db->ReleaseSnapshot(readOptions.snapshot);

    delete db;
}

Console:

2014-09-30 14:41:19.354 RockyPlay[17407:1056596] value:super duper
(lldb) <-- crash

Stack trace:

Thread 1Queue : com.apple.main-thread (serial)
#0  0x0006dc4e in rocksdb::Version::LevelFileNumIterator::key() const ()
#1  0x00092670 in rocksdb::(anonymous namespace)::TwoLevelIterator::SeekToFirst() ()
#2  0x0008b1ca in rocksdb::MergingIterator::SeekToFirst() ()
#3  0x00045590 in rocksdb::DBIter::SeekToFirst() ()
#4  0x00045ca4 in rocksdb::ArenaWrappedDBIter::SeekToFirst() ()
#5  0x0000a420 in +[SemiRocksDB internalIterationTest] at ~ ... RockyPlay/SemiRocksDB.mm:102

Debugger

RockyPlay`rocksdb::(anonymous namespace)::TwoLevelIterator::SeekToFirst():
0x92640:  pushl  %ebp
0x92641:  movl   %esp, %ebp
0x92643:  pushl  %esi
0x92644:  pushl  %eax
0x92645:  movl   0x8(%ebp), %esi
0x92648:  movl   0x18(%esi), %eax
0x9264b:  movl   (%eax), %ecx
0x9264d:  movl   %eax, (%esp)
0x92650:  calll  *0xc(%ecx)
0x92653:  movl   0x18(%esi), %eax
0x92656:  movl   (%eax), %ecx
0x92658:  movl   %eax, (%esp)
0x9265b:  calll  *0x8(%ecx)
0x9265e:  movb   %al, 0x1c(%esi)
0x92661:  testb  %al, %al
0x92663:  je     0x92676                   ; rocksdb::(anonymous namespace)::TwoLevelIterator::SeekToFirst() + 54
0x92665:  movl   0x18(%esi), %eax
0x92668:  movl   (%eax), %ecx
0x9266a:  movl   %eax, (%esp)
0x9266d:  calll  *0x20(%ecx)
0x92670:  movl   %edx, 0x24(%esi)   <----- EXC_BAD_ACCESS (code=2, address=0x1d)
0x92673:  movl   %eax, 0x20(%esi)
0x92676:  movl   %esi, %ecx
0x92678:  calll  0x92b40                   ; rocksdb::(anonymous namespace)::TwoLevelIterator::InitDataBlock()
0x9267d:  movl   0x28(%esi), %eax
0x92680:  testl  %eax, %eax
0x92682:  je     0x926af                   ; rocksdb::(anonymous namespace)::TwoLevelIterator::SeekToFirst() + 111
0x92684:  movl   (%eax), %ecx
0x92686:  movl   %eax, (%esp)
0x92689:  calll  *0xc(%ecx)
0x9268c:  movl   0x28(%esi), %eax
0x9268f:  movl   (%eax), %ecx
0x92691:  movl   %eax, (%esp)
0x92694:  calll  *0x8(%ecx)
0x92697:  movb   %al, 0x2c(%esi)
0x9269a:  testb  %al, %al
0x9269c:  je     0x926af                   ; rocksdb::(anonymous namespace)::TwoLevelIterator::SeekToFirst() + 111
0x9269e:  movl   0x28(%esi), %eax
0x926a1:  movl   (%eax), %ecx

The text was updated successfully, but these errors were encountered:

semireg · 2014-10-01T01:08:21Z

I think there are multiple issues with the LITE builds. First, when I clone the current repo and run this:

$ TARGET_OS=IOS make static_lib
$ cd examples/
$ make
$ ./simple_example
Assertion failed: (s.ok()), function main, file simple_example.cc, line 27.
Abort trap: 6

Is anyone else seeing this?

igorcanadi · 2014-10-01T01:12:08Z

You also need to compile simple_example using -DROCKSDB_LITE

semireg · 2014-10-01T01:13:38Z

Ok, I just tried that. Same error with assertion failed.

$ TARGET_OS=IOS make
g++  simple_example.cc -osimple_example ../librocksdb.a -I../include -O2 -std=c++11  -std=c++11  -DROCKSDB_PLATFORM_POSIX  -DOS_MACOSX -DIOS_CROSS_COMPILE -DROCKSDB_LITE
g++  column_families_example.cc -ocolumn_families_example ../librocksdb.a -I../include -O2 -std=c++11  -std=c++11  -DROCKSDB_PLATFORM_POSIX  -DOS_MACOSX -DIOS_CROSS_COMPILE -DROCKSDB_LITE
$ ./simple_example
Assertion failed: (s.ok()), function main, file simple_example.cc, line 27.
Abort trap: 6

semireg · 2014-10-01T01:18:02Z

I added a bit more debugging:

$ls -lah /tmp/rocksdb_simple_example/
ls: /tmp/rocksdb_simple_example/: No such file or directory

$./simple_example
error:IO error: `/tmp/rocksdb_simple_example' exists but is not a directory
Assertion failed: (s.ok()), function main, file simple_example.cc, line 29.
Abort trap: 6

$ls -lah /tmp/rocksdb_simple_example/
total 8
drwxr-xr-x   3 i     wheel   102B Sep 30 20:17 .
drwxrwxrwt  19 root  wheel   646B Sep 30 20:17 ..
-rw-r--r--   1 i     wheel   3.5K Sep 30 20:17 LOG

$cat /tmp/rocksdb_simple_example/LOG
2014/09/30-20:17:05.917806 7fff7eb7a310 DB SUMMARY
2014/09/30-20:17:05.918198 7fff7eb7a310 SST files in /tmp/rocksdb_simple_example dir, Total Num: 0, files:
2014/09/30-20:17:05.918203 7fff7eb7a310 Write Ahead Log file in /tmp/rocksdb_simple_example:
2014/09/30-20:17:05.918205 7fff7eb7a310          Options.error_if_exists: 0
2014/09/30-20:17:05.918206 7fff7eb7a310        Options.create_if_missing: 1
2014/09/30-20:17:05.918208 7fff7eb7a310          Options.paranoid_checks: 1
2014/09/30-20:17:05.918209 7fff7eb7a310                      Options.env: 0x106608d50
2014/09/30-20:17:05.918210 7fff7eb7a310                 Options.info_log: 0x7fe5c3c11a30
2014/09/30-20:17:05.918212 7fff7eb7a310           Options.max_open_files: 5000
2014/09/30-20:17:05.918213 7fff7eb7a310       Options.max_total_wal_size: 0
2014/09/30-20:17:05.918214 7fff7eb7a310        Options.disableDataSync: 0
2014/09/30-20:17:05.918216 7fff7eb7a310              Options.use_fsync: 0
2014/09/30-20:17:05.918217 7fff7eb7a310      Options.max_log_file_size: 0
2014/09/30-20:17:05.918218 7fff7eb7a310 Options.max_manifest_file_size: 18446744073709551615
2014/09/30-20:17:05.918220 7fff7eb7a310      Options.log_file_time_to_roll: 0
2014/09/30-20:17:05.918221 7fff7eb7a310      Options.keep_log_file_num: 1000
2014/09/30-20:17:05.918222 7fff7eb7a310        Options.allow_os_buffer: 1
2014/09/30-20:17:05.918224 7fff7eb7a310       Options.allow_mmap_reads: 0
2014/09/30-20:17:05.918225 7fff7eb7a310      Options.allow_mmap_writes: 0
2014/09/30-20:17:05.918226 7fff7eb7a310          Options.create_missing_column_families: 0
2014/09/30-20:17:05.918227 7fff7eb7a310                              Options.db_log_dir:
2014/09/30-20:17:05.918229 7fff7eb7a310                                 Options.wal_dir: /tmp/rocksdb_simple_example
2014/09/30-20:17:05.918230 7fff7eb7a310                Options.table_cache_numshardbits: 4
2014/09/30-20:17:05.918231 7fff7eb7a310     Options.table_cache_remove_scan_count_limit: 16
2014/09/30-20:17:05.918233 7fff7eb7a310     Options.delete_obsolete_files_period_micros: 21600000000
2014/09/30-20:17:05.918234 7fff7eb7a310              Options.max_background_compactions: 15
2014/09/30-20:17:05.918235 7fff7eb7a310                  Options.max_background_flushes: 1
2014/09/30-20:17:05.918237 7fff7eb7a310                         Options.WAL_ttl_seconds: 0
2014/09/30-20:17:05.918238 7fff7eb7a310                       Options.WAL_size_limit_MB: 0
2014/09/30-20:17:05.918239 7fff7eb7a310             Options.manifest_preallocation_size: 4194304
2014/09/30-20:17:05.918241 7fff7eb7a310                          Options.allow_os_buffer: 1
2014/09/30-20:17:05.918242 7fff7eb7a310                         Options.allow_mmap_reads: 0
2014/09/30-20:17:05.918243 7fff7eb7a310                        Options.allow_mmap_writes: 0
2014/09/30-20:17:05.918244 7fff7eb7a310                      Options.is_fd_close_on_exec: 1
2014/09/30-20:17:05.918246 7fff7eb7a310               Options.skip_log_error_on_recovery: 0
2014/09/30-20:17:05.918247 7fff7eb7a310                    Options.stats_dump_period_sec: 3600
2014/09/30-20:17:05.918248 7fff7eb7a310                    Options.advise_random_on_open: 1
2014/09/30-20:17:05.918250 7fff7eb7a310          Options.access_hint_on_compaction_start: NORMAL
2014/09/30-20:17:05.918253 7fff7eb7a310                       Options.use_adaptive_mutex: 0
2014/09/30-20:17:05.918254 7fff7eb7a310                             Options.rate_limiter: 0x0
2014/09/30-20:17:05.918255 7fff7eb7a310                           Options.bytes_per_sync: 1048576

semireg · 2014-10-01T01:20:28Z

Earlier I did some digging to try and figure out why S_ISDIR was returning 0 for the mode of the directory. I'm still not sure why building with ROCKSDB_LITE makes a difference.

From util/env_posix.cc:1474

  // Returns true iff the named directory exists and is a directory.
  virtual bool DirExists(const std::string& dname) {
    struct stat statbuf;
    if (stat(dname.c_str(), &statbuf) == 0) {
      return S_ISDIR(statbuf.st_mode);
    }
    return false; // stat() failed return false
  }

igorcanadi · 2014-10-01T01:29:57Z

Are you running on mac OS or ios simulator?

semireg · 2014-10-01T13:35:03Z

This is a complex issue with at least 3 bugs affecting different runtimes (e.g. simulator vs. OSX command line).

The original issue of EXC_BAD_ACCESS occurs on the iOS Simulator as well as on physical iOS devices.

When I try to replicate the issue on the OSX command line (compiled using ROCKSDB_LITE), I am struck with the other bugs such as "IO error: `/tmp/rocksdb_simple_example' exists but is not a directory." The show-stopper for me is the original crash... but the other bugs makes troubleshooting difficult, if not impossible.

igorcanadi · 2014-10-01T17:26:58Z

Can you try compiling your project with ROCKSDB_LITE and running it on iOS simulator? I'm 99% confident that EXC_BAD_ACCESS occurs because you didn't compile your project with ROCKSDB_LITE.

I can repro the other issue on my mac. It looks like fs system calls are funky when running iOS binaries on OSX. I don't have much experience here and can't help unfortunately.

semireg · 2014-10-01T18:04:13Z

When you say "project" do you mean the Xcode project? Which build setting should I modify? Can you post a screenshot?

Caylan

On Oct 1, 2014, at 12:27 PM, Igor Canadi notifications@github.com wrote:

Can you try compiling your project with ROCKSDB_LITE and running it on iOS simulator? I'm 99% confident that EXC_BAD_ACCESS occurs because you didn't compile your project with ROCKSDB_LITE.

I can repro the other issue on my mac. It looks like fs system calls are funky when running iOS binaries on OSX. I don't have much experience here and can't help unfortunately.

—
Reply to this email directly or view it on GitHub.

igorcanadi · 2014-10-01T18:12:01Z

There must be some sort of compile flags, right? Just add -DROCKSDB_LITE to compile flags in Xcode.

igorcanadi · 2014-10-01T18:13:03Z

Maybe try "preprocessor macros"?

igorcanadi · 2014-10-01T18:14:22Z

Also add IOS_CROSS_COMPILE.

igorcanadi · 2014-10-01T18:15:57Z

Added this to our INSTALL.md: https://github.com/facebook/rocksdb/blob/master/INSTALL.md

semireg · 2014-10-01T18:54:02Z

I recompiled everything, added flags wherever I thought relevant, and it's still crashing.

semireg · 2014-10-01T18:54:25Z

I cleaned both the project build, and I cleaned and rebuilt the static lib.

igorcanadi · 2014-11-14T18:40:50Z

@semireg it looks like we might have fixed this error by fa50abb. Can you please check if it works now?

We are starting to more actively support our iOS builds. Sorry about non-support so far.

igorcanadi · 2014-11-24T16:14:30Z

Any news?

igorcanadi · 2015-01-24T02:43:32Z

This issue is likely fixed by fa50abb. Feel free to reopen if you are still seeing this.

⬆️ bump prebuild

Summary: This linker flag does not seem to be needed, and prevents use of gold or lld at link time. Test Plan: * build using llvm thinLTO

igorcanadi closed this as completed Jan 24, 2015

Nazgolze pushed a commit to Nazgolze/rocksdb-1 that referenced this issue Sep 21, 2021

Merge pull request facebook#325 from ralphtheninja/master

744e60b

⬆️ bump prebuild

rockeet pushed a commit to rockeet/rocksdb that referenced this issue Oct 5, 2024

remove --copy-dt-needed-entries when linking exes (facebook#325)

a963bbf

Summary: This linker flag does not seem to be needed, and prevents use of gold or lld at link time. Test Plan: * build using llvm thinLTO

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EXC_BAD_ACCESS on ROCKSDB_LITE, iOS Simulator #325

EXC_BAD_ACCESS on ROCKSDB_LITE, iOS Simulator #325

semireg commented Sep 30, 2014

semireg commented Oct 1, 2014

igorcanadi commented Oct 1, 2014

semireg commented Oct 1, 2014

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igorcanadi commented Jan 24, 2015

EXC_BAD_ACCESS on ROCKSDB_LITE, iOS Simulator #325

EXC_BAD_ACCESS on ROCKSDB_LITE, iOS Simulator #325

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semireg commented Sep 30, 2014

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