Tasks stuck for weeks

From the task queue page: Running Project Build Package Name Package Version Chroot 19 days rpmsoftwaremanagement/dnf-nightly 835447 dnf-plugins-core 4.0.2-6g675369a.fc26 fedora-27-x86_64 17 days rpmsoftwaremanagement/dnf-nightly 835834 libsolv 0.7.2-1g2645bc64.fc26 fedora-27-x86_64 4 days rpmsoftwaremanagement/dnf-nightly 836102 libsolv 0.7.2-1g2645bc64.fc26 fedora-27-x86_64 15 days rpmsoftwaremanagement/dnf-nightly 836675 libsolv 0.7.2-11g95dcddc7.fc26 fedora-27-x86_64 4 days rpmsoftwaremanagement/dnf-nightly 837116 libsolv 0.7.2-11g95dcddc7.fc26 fedora-27-x86_64 11 days rpmsoftwaremanagement/dnf-nightly 837960 libsolv 0.7.2-11g95dcddc7.fc26 fedora-27-x86_64 10 days rpmsoftwaremanagement/dnf-nightly 838163 libsolv 0.7.2-11g95dcddc7.fc26 fedora-27-x86_64 9 days rpmsoftwaremanagement/dnf-nightly 838447 libsolv 0.7.2-15ge90ef867.fc26 fedora-27-x86_64 20 minutes @dotnet-sig/dotnet-preview 839046 dotnet 3.0.0-0.1.preview1.fc30 fedora-29-x86_64 6 days nalimilan/julia-nightlies 839415 llvm6 6.0.0-4.fc26 fedora-29-x86_64 4 days rpmsoftwaremanagement/dnf-nightly 839671 libsolv 0.7.2-18gd8a0a671.fc26 fedora-27-x86_64 4 days rpmsoftwaremanagement/dnf-nightly 839773 libsolv 0.7.2-18gd8a0a671.fc26 fedora-27-x86_64 54 minutes avik/boost 840375 boost 1.66.0-15.1.scylladb.fc29 fedora-29-x86_64 1 minute surfernsk/Personal_repos 840377 qbittorrent 1:4.1.5-1.fc28 fedora-28-x86_64 4 minutes surfernsk/Personal_repos 840377 qbittorrent 1:4.1.5-1.fc28 fedora-rawhide-i386 4 minutes surfernsk/Personal_repos 840377 qbittorrent 1:4.1.5-1.fc28 fedora-rawhide-x86_64 11 minutes surfernsk/Personal_repos 840377 qbittorrent 1:4.1.5-1.fc28 fedora-29-i386 4 minutes scylladb/toolchain 840378 boost 1.66.0-15.1.scylladb.fc29 fedora-29-ppc64le Looks like there are several tasks stuck for many days. I expect they are zombies, but perhaps they are consuming execution slots and preventing other tasks from running.