Error 500 on heavy load.

I have experienced a strange behaviour over the REST interface using node-fetch module.

While this is not the most efficient way of doing things, it has thrown up the following error 500.

I read in around 11 ttl files so that total about 1,6m triples. I now want to pivot them and create a file per subject. I process each of the 1,6m triples as set out below. Check whether the resource exists. If it does not, create it using PUT, else PATCH in the new triple.

For logging I write out a 'pulse' every 5,000 records.

The code below is an extract of the process.

   let getResult = await fetch(newUrl, {method: "HEAD"})
//                console.log(getResult.status)
                if (getResult.status === 404) {
                    options = {
                        method: "PUT",
                        headers: {
                            "content-type" : "text/turtle",
                            "Link": "<http://www.w3.org/ns/ldp#Resource>; rel='type'"
                        },
                        body: `${newSubject} <${newPredicate}> ${newObject} .`
                   }
                }
                else {
                    options = {
                        method: "PATCH",
                        headers: {
                            "content-type" : "application/sparql-update",
                            "Link": "<http://www.w3.org/ns/ldp#Resource>; rel='type'"
                        },
                        body: `INSERT DATA { ${newSubject} <${newPredicate}> ${newObject} }`
                    }
                };
                let res1 = await fetch(newUrl, options);
                if ((res1.status != 200) && (res1.status != 201)) console.log("PROBLEMS WITH THE SOLID-SERVER", res1.status, JSON.stringify(options));
                if ( i % 5000 === 0) console.log("output", i, newUrl, res1.status);
 

Just after the 80,000th log entry and before the 85,000th log entry, the server starts producing error 500 and never recovers. As can be seen in the output below:

...
output 75000 https://127.0.0.1:8443/eim/App_Inst/714101 200
output 80000 https://127.0.0.1:8443/eim/App_Inst/876505 200
PROBLEMS WITH THE SOLID-SERVER 500 {"method":"PUT","headers":{"content-type":"text/turtle","Link":"<http://www.w3.org/ns/ldp#Resource>; rel='type'"},"body":"<> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <https://127.0.0.1:8443/eim/App_Instance_Review> ."}
PROBLEMS WITH THE SOLID-SERVER 500 {"method":"PUT","headers":{"content-type":"text/turtle","Link":"<http://www.w3.org/ns/ldp#Resource>; rel='type'"},"body":"<> <https://127.0.0.1:8443/eim/App_Inst_ID> \"\" ."}
...

從 REST 介面開始，使用回報的 PUT 和 PATCH 請求，重現處理約 160 萬個三元組的 node-fetch 工作負載。調查伺服器為何在大約 80,000 筆記錄後開始回傳 HTTP 500 回應，以及它是否會恢復；當該工作負載不再產生持續性的 500 錯誤，且該故障已由適當的測試或重現涵蓋時，即視為完成。