Abstract: The downhole pump has a barrel with a reciprocating plunger therein. The barrel has a first one-way valve, while the plunger has a second one-way valve. A barrel chamber is formed between the two one-way valves. The barrel chamber expands when the reciprocal movement between the plunger and the barrel is an upstroke movement and then contracts when the reciprocal movement is a downstroke movement. A bypass channel is provided between the barrel and the plunger so as to provide communication around the plunger and its one-way valve. The bypass channel is open when the reciprocal movement is near an end of the upstroke movement. When open, pressure across the plunger can equalize and gas inside the barrel chamber can vent around the plunger and/or pressure can equalize across the plunger one-way valve so as to prevent gas lock and minimize stress on the sucker rods.