  We present the complete azimuthal asymmetries at leading twist in terms of
fragmentation functions in dihadron production semi-inclusive electron positron
annihilation process. When the non-trivial $\theta$ vacuum is taken into
consideration, the parity symmetry of quantum chromodynamics is violated. As a
consequence of the $local$ $\mathcal{P}$-odd effects, $\mathcal{P}$-odd
fragmentation functions would contribute to the azimuthal asymmetries.
Azimuthal asymmetry coming from two interference terms with opposite signs
vanishes when sum over many events. This symmetry only survives on the
event-by-event basis. Azimuthal asymmetry coming from two interference terms
with same signs survives and can be measured to extract the $\mathcal{P}$-odd
fragmentation functions. We also present the hadron polarizations.
