PP freezes waiting for SM to answer over a socket

TID 3950697:

#0  0x00007fd55013345c pthread_cond_wait@@GLIBC_2.3.2

#1  0x0000556694d242eb primitiveprocessor::prefetchBlocks(unsigned long, int, unsigned int*)

#2  0x0000556694d24e50 primitiveprocessor::loadBlocks(long*, BRM::QueryContext, int, int, unsigned char**, unsigned int*, bool, unsigned int, unsigned int, bool*, bool, std::tr1::unordered_map<long, BRM::VSSData, std::tr1::hash<long>, std::equal_to<long>, std::allocator<std::pair<long const, BRM::VSSData> > >*)

#3  0x0000556694d08822 void primitiveprocessor::ColumnCommand::_loadData<8>()

#4  0x0000556694d0545d primitiveprocessor::ColumnCommand::issuePrimitive()

#5  0x0000556694d01ef4 primitiveprocessor::ColumnCommand::projectIntoRowGroup(rowgroup::RowGroup&, unsigned int)

#6  0x0000556694ceb50f primitiveprocessor::BatchPrimitiveProcessor::execute()

#7  0x0000556694cee1a1 primitiveprocessor::BatchPrimitiveProcessor::operator()()

#8  0x0000556694cfb48d primitiveprocessor::BPPSeeder::operator()()

#9  0x00007fd54fed8ac3 threadpool::FairThreadPool::threadFcn(threadpool::PriorityThreadPool::Priority)

#10 0x0000556694d42c97 thread_proxy

#11 0x00007fd55012d1ca start_thread

#12 0x00007fd54eb3de73 __clone

..

TID 3950869:

#0  0x00007fd550136ab4 read

#1  0x00007fd54def394b idbdatafile::SocketPool::send_recv(messageqcpp::ByteStream&, messageqcpp::ByteStream*)

#2  0x00007fd54dee912e idbdatafile::SMComm::pread(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, void*, unsigned long, long)

#3  0x0000556694d54fac (anonymous namespace)::thr_popper(dbbc::ioManager*)

#4  0x0000556694d59970 boost::detail::thread_data<dbbc::LambdaKludge>::run()

#5  0x0000556694d42c97 thread_proxy

#6  0x00007fd55012d1ca start_thread

#7  0x00007fd54eb3de73 __clone