The only thing that has ever cracked my jars was an extreme change in temperature. I have two rapid boil canners: one is a heavy, metal, very old with a glass top, 4 jar canner; one is a new lighter metal, spatterware, 7 jar canner--both have dividers. I either start with cold jars in cold water, OR I dip the jars in scalding water, fill with scalding hot ingredients, then put into boiling water, set the timer, check my lids, etc. Lukewarm jars and hot water has cracked jars for me in the past, and they have cracked solidly in half, or the bottoms have cracked off.
BTW, there are a few jars that I have gotten by buying another product, and the screw lids fit the jars. For some reason a lot of manufacturers, whose jars USED to fit canning lids, have made them smaller or larger, but you cannot reuse, say, a spaghetti sauce or mayonnaise glass jar anymore for your canning. Too bad.
