Those two methods already use FastMutex::ScopedLock lock(_mutex), but
the scope is not large enough to protect "NotifierPtr pNotifier" that is
accessed by calling SocketNotifier::addObserver() and
SocketNotifier::removeObserver().
It is mentioned in SocketReator.h that it is safe to call
addEventHandler() and removeEventHandler() from another thread while the
SocketReactor is running. My current use of the SocketReactor
encountered an issue where the SocketNotifier::_events has been
corrupted by a concurent write access done by
SocketReactor::addEventHandler() and
SocketReactor::removeEventHandler().
The call stack show that the SocketReactor::addEventHandler is stuck in
a while loop in gcc/libstdc++/tree.cc Rb_tree_insert_and_rebalance()
I clearly see in my logs that it happened while my
SocketConnector::unregisterConnector() and
SocketConnector::registerConnector() were called by two different
threads.
#0 0x00a80a7b in std::_Rb_tree_insert_and_rebalance () from
/usr/lib/libstdc++.so.6
#1 0x06ccb430 in std::_Rb_tree<Poco::Net::SocketNotification*,
Poco::Net::SocketNotification*,
std::_IdentityPoco::Net::SocketNotification*,
std::lessPoco::Net::SocketNotification*,
std::allocatorPoco::Net::SocketNotification* >::_M_insert
(this=0xac75dc90, __x=0x0, __p=0xac7ed0c8, __v=@0xb5fb0c40) at
/usr/lib/gcc/i386-redhat-linux/3.4.6/../../../../include/c++/3.4.6/bits/stl_tree.h:816
#2 0x06ccb15d in std::_Rb_tree<Poco::Net::SocketNotification*,
Poco::Net::SocketNotification*,
std::_IdentityPoco::Net::SocketNotification*,
std::lessPoco::Net::SocketNotification*,
std::allocatorPoco::Net::SocketNotification* >::insert_equal
(this=0xac75dc90, __v=@0xb5fb0c40) at
/usr/lib/gcc/i386-redhat-linux/3.4.6/../../../../include/c++/3.4.6/bits/stl_tree.h:858
#3 0x06ccad86 in std::multiset<Poco::Net::SocketNotification*,
std::lessPoco::Net::SocketNotification*,
std::allocatorPoco::Net::SocketNotification* >::insert (this=0xac75dc90,
__x=@0xb5fb0c40)
at
/usr/lib/gcc/i386-redhat-linux/3.4.6/../../../../include/c++/3.4.6/bits/stl_multiset.h:306
#4 0x06cca72b in Poco::Net::SocketNotifier::addObserver
(this=0xac75dc70, pReactor=0x8d27958, observer=@0xb5fb0cd0) at
src/SocketNotifier.cpp:45
#5 0x06cd060f in Poco::Net::SocketReactor::addEventHandler
(this=0x8d27958, socket=@0xac7f5a74, observer=@0xb5fb0cd0) at
src/SocketReactor.cpp:178
SocketReactor::run() is already protecting the access to the
SocketNotifier.
* SQlite 3.19.3
changelog
http://www.sqlite.org/releaselog/3_19_3.html
* epoll_event memset fix
with -std=c++14 the sizeof(eventsIn) give as result the number of array elements not the bytes number, so the memset is wrong
* fix for older gcc
on older version of gcc struct epoll_event eventsOut[epollSize] = { 0 }; does not compile
SO_REUSEADDR is to reuse a socket in time-wait state, this is often turned on
by server applicationis, but if a port is being used, the server could fail,
this is expected. But with SO_REUSEPORT option, it even can open a port which
is being used, this is a more error prone than SO_REUSEADDR, because we
normally don't want to share a port with irrelevant application without
notice, the behavior should not be default.
