A large-scale, up-to-date analysis of Computer Science literature (11.8M papers through 2019) reveals that, if trends from the last 50 years continue, parity between the number of male and female authors will not be reached in this century. In contrast, parity is projected to be reached within two to three decades or may have already been reached in other fields of study like Medicine or Sociology. Our analysis of collaboration trends in Computer Science reveals shifts in the size of the collaboration gap between authors of different perceived genders. The gap is persistent but shrinking, corresponding to a slow increase in the rate of cross-gender collaborations over time. Together, these trends describe a persistent gender gap in the authorship of Computer Science literature that may not close without systematic intervention.