  At RHIC kinematics, polarized jet hadroproduction is dominated by $gg$ and
$qg$ scattering, making the jet longitudinal double-spin asymmetry, $A_{LL}$,
sensitive to gluon polarization in the nucleon. I will present STAR results of
$A_{LL}$ from inclusive jet and dijet measurements for the RHIC 2006 run
totaling 5.5 pb$^{-1}$ of integrated luminosity with 55% beam polarization at
center-of-mass energy 200 GeV. I will also present preliminary results from the
analyses of data from the 2009 run, which collected a much larger sample (25
pb$^{-1}$ with 57% polarization) at 200 GeV. The results are compared with
theoretical calculations of $A_{LL}$ based on various models of the polarized
gluon distribution function in the nucleon. The STAR data place significant
constraints on allowed theoretical models.
