Application: akonadi_baloo_indexer (4.14)
KDE Platform Version: 4.14.34
Qt Version: 4.8.7
Operating System: Linux 4.15.0-041500rc6-generic x86_64
Distribution: Ubuntu 17.10

-- Information about the crash:
Because of bugs in GMail IMAP handling, restarting Akonadi periodically is required (...)

The akonadi_baloo_indexer is the only process belonging to akonadi stuff that _never_ exits cleanly:

org.kde.pim.akonadicontrol: ProcessControl: Application "/usr/bin/akonadi_baloo_indexer" stopped unexpectedly ( "Process crashed" )
org.kde.pim.akonadicontrol: Application '/usr/bin/akonadi_baloo_indexer' crashed! 1 restarts left.
QProcess: Destroyed while process ("/usr/bin/akonadi_baloo_indexer") is still running.
org.kde.pim.akonadicontrol: ProcessControl: Application "/usr/bin/akonadi_baloo_indexer" stopped unexpectedly ( "Process crashed" )
org.kde.pim.akonadicontrol: Application '/usr/bin/akonadi_baloo_indexer' crashed! 0 restarts left.
org.kde.pim.akonadicontrol: Agent instance with identifier "akonadi_baloo_indexer" does not exist
akonadi_baloo_indexer(12481): "DatabaseLockError" "DatabaseLockError: Unable to get write lock on /home/dean/.local/share/baloo/email/: already locked" 
akonadi_baloo_indexer(12481): "DatabaseLockError" "DatabaseLockError: Unable to get write lock on /home/dean/.local/share/baloo/emailContacts/: already locked"

The crash can be reproduced every time.

-- Backtrace:
Application:  (akonadi_baloo_indexer), signal: Aborted
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[KCrash Handler]
#6  0x00007feb46cd70bb in __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:51
#7  0x00007feb46cd8f5d in __GI_abort () at abort.c:90
#8  0x00007feb4a8a8f15 in qt_message_output(QtMsgType, char const*) () at /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#9  0x00007feb493ddcc7 in  () at /usr/lib/libakonadi-kde.so.4
#10 0x00007feb493dd18a in  () at /usr/lib/libakonadi-kde.so.4
#11 0x00007feb4a9ddd11 in QObject::event(QEvent*) () at /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#12 0x00007feb47f3103c in QApplicationPrivate::notify_helper(QObject*, QEvent*) () at /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#13 0x00007feb47f37f76 in QApplication::notify(QObject*, QEvent*) () at /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#14 0x00007feb48c9004a in KApplication::notify(QObject*, QEvent*) () at /usr/lib/libkdeui.so.5
#15 0x00007feb4a9c38ad in QCoreApplication::notifyInternal(QObject*, QEvent*) () at /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#16 0x00007feb4a9c7366 in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) () at /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#17 0x00007feb4a9f409e in  () at /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#18 0x00007feb46396fb7 in g_main_context_dispatch () at /lib/x86_64-linux-gnu/libglib-2.0.so.0
#19 0x00007feb463971f0 in  () at /lib/x86_64-linux-gnu/libglib-2.0.so.0
#20 0x00007feb4639727c in g_main_context_iteration () at /lib/x86_64-linux-gnu/libglib-2.0.so.0
#21 0x00007feb4a9f420e in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#22 0x00007feb47fde666 in  () at /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#23 0x00007feb4a9c212f in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#24 0x00007feb4a9c2495 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#25 0x00007feb4a9c8459 in QCoreApplication::exec() () at /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#26 0x00007feb493da43d in Akonadi::AgentBase::init(Akonadi::AgentBase*) () at /usr/lib/libakonadi-kde.so.4
#27 0x000055d5cb5731f3 in  ()
#28 0x00007feb46cc11c1 in __libc_start_main (main=0x55d5cb56c3a0, argc=3, argv=0x7ffe6b46e778, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7ffe6b46e768) at ../csu/libc-start.c:308
#29 0x000055d5cb56c45a in _start ()

Reported using DrKonqi