We had experienced deadlocks with some standard 'Select' queries provided by Activiti on the following tables: ACT_RU_TASK, ACT_RU_EXECUTION and ACT_RE_PROCDEF. Here is an example query:
### SQL: SELECT SUB.* FROM ( select distinct TEMPRES_ID_ as ID_, TEMPP_KEY_ as ProcessDefinitionKey, TEMPP_ID_ as ProcessDefinitionId, TEMPRES_REV_ as REV_, TEMPRES_ACT_ID_ as ACT_ID_, TEMPRES_BUSINESS_KEY_ as BUSINESS_KEY_, TEMPRES_IS_ACTIVE_ as IS_ACTIVE_, TEMPRES_IS_CONCURRENT_ as IS_CONCURRENT_, TEMPRES_IS_SCOPE_ as IS_SCOPE_, TEMPRES_IS_EVENT_SCOPE_ as IS_EVENT_SCOPE_, TEMPRES_PARENT_ID_ as PARENT_ID_, TEMPRES_PROC_INST_ID_ as PROC_INST_ID_, TEMPRES_SUPER_EXEC_ as SUPER_EXEC_, TEMPRES_SUSPENSION_STATE_ as SUSPENSION_STATE_, TEMPRES_CACHED_ENT_STATE_ as CACHED_ENT_STATE_, TEMPVAR_ID_ as VAR_ID_, TEMPVAR_NAME_ as VAR_NAME_, TEMPVAR_TYPE_ as VAR_TYPE_, TEMPVAR_REV_ as VAR_REV_, TEMPVAR_PROC_INST_ID_ as VAR_PROC_INST_ID_, TEMPVAR_EXECUTION_ID_ as VAR_EXECUTION_ID_, TEMPVAR_TASK_ID_ as VAR_TASK_ID_, TEMPVAR_BYTEARRAY_ID_ as VAR_BYTEARRAY_ID_, TEMPVAR_DOUBLE_ as VAR_DOUBLE_, TEMPVAR_TEXT_ as VAR_TEXT_, TEMPVAR_TEXT2_ as VAR_TEXT2_, TEMPVAR_LONG_ as VAR_LONG_ , row_number() over (ORDER BY TEMPRES_ID_ asc) rnk FROM ( select distinct RES.ID_ as TEMPRES_ID_, RES.REV_ as TEMPRES_REV_, P.KEY_ as TEMPP_KEY_, P.ID_ as TEMPP_ID_, RES.ACT_ID_ as TEMPRES_ACT_ID_, RES.PROC_INST_ID_ as TEMPRES_PROC_INST_ID_, RES.BUSINESS_KEY_ as TEMPRES_BUSINESS_KEY_, RES.IS_ACTIVE_ as TEMPRES_IS_ACTIVE_, RES.IS_CONCURRENT_ as TEMPRES_IS_CONCURRENT_, RES.IS_SCOPE_ as TEMPRES_IS_SCOPE_, RES.IS_EVENT_SCOPE_ as TEMPRES_IS_EVENT_SCOPE_, RES.PARENT_ID_ as TEMPRES_PARENT_ID_, RES.SUPER_EXEC_ as TEMPRES_SUPER_EXEC_, RES.SUSPENSION_STATE_ as TEMPRES_SUSPENSION_STATE_, RES.CACHED_ENT_STATE_ as TEMPRES_CACHED_ENT_STATE_, VAR.ID_ as TEMPVAR_ID_, VAR.NAME_ as TEMPVAR_NAME_, VAR.TYPE_ as TEMPVAR_TYPE_, VAR.REV_ as TEMPVAR_REV_, VAR.PROC_INST_ID_ as TEMPVAR_PROC_INST_ID_, VAR.EXECUTION_ID_ as TEMPVAR_EXECUTION_ID_, VAR.TASK_ID_ as TEMPVAR_TASK_ID_, VAR.BYTEARRAY_ID_ as TEMPVAR_BYTEARRAY_ID_, VAR.DOUBLE_ as TEMPVAR_DOUBLE_, VAR.TEXT_ as TEMPVAR_TEXT_, VAR.TEXT2_ as TEMPVAR_TEXT2_, VAR.LONG_ as TEMPVAR_LONG_ from ACT_RU_EXECUTION RES inner join ACT_RE_PROCDEF P on RES.PROC_DEF_ID_ = P.ID_ left outer join ACT_RU_VARIABLE VAR ON RES.PROC_INST_ID_ = VAR.EXECUTION_ID_ and VAR.TASK_ID_ is null WHERE RES.PARENT_ID_ is null and P.KEY_ = ? and RES.BUSINESS_KEY_ = ? )RES ) SUB WHERE SUB.rnk >= ? AND SUB.rnk < ?
Activiti version is 5.15.1, I have changed the version now I use 5.22.0 but the problem it isn't resolved.
Does anyone experienced something similar, or does anyone have an idea to start understanding why this happens and how to prevent it?
I use sql server.